Re: [CentOS-virt] Upgrade to CentOS 7.6 with centos-xen-48 enabled

[Scot P. Floess]

On Sun, 23 Dec 2018, Gennardy Smith wrote:

Just to answer my own question, I solved this by installing 
yum-plugin-priorities

and setting priority=10 to centos-virt-xen-48 repository.

Yum doesn't consider the libvirt packages from CentOS base/updates anymore
after this.

Sorry for the noise,

Gennardy

On 23.12.18 11:01, Gennardy Smith wrote:

Hi all,

I'm unable to upgrade my Dom-0 from CentOS 7.5 to CentOS 7.6 with the 
sigvirt

centos-xen-48 repository enabled and Xen components enabled.

It breaks down to down to the fact that 7.6 has a newer version of 
libvirt

included (4.5), while the Xen repository's packages are build against 4.1
version of libvirt.

I also tried to enable the libvirt-latest repository, but that does not
contain libvirt-daemon-driver-xen package, so dependency resolution is
broken again.

Is there some workaround for this, or do I just have to wait for the Xen
repository to be updated? Has someone resolved this problem?

Regards,
G.

The following is the output of yum when running yum update:

[user@dom0 ~]$ sudo yum update
[...]
--> Finished Dependency Resolution
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-driver-libxl-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-network-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-network-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-network = 3.2.1-480.el7
   Available: 
libvirt-daemon-driver-network-4.5.0-10.el7.x86_64 (base)

   libvirt-daemon-driver-network = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon = 4.1.0-2.xen48.el7
   Removing: libvirt-daemon-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon = 4.1.0-2.xen48.el7
   Updated By: libvirt-daemon-4.5.0-10.el7_6.3.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.3
   Available: libvirt-daemon-3.2.1-480.el7.x86_64 
(centos-virt-xen-48)

   libvirt-daemon = 3.2.1-480.el7
   Available: libvirt-daemon-4.5.0-10.el7.x86_64 (base)
   libvirt-daemon = 4.5.0-10.el7
   Available: libvirt-daemon-4.5.0-10.el7_6.2.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-nwfilter-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-nwfilter-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 3.2.1-480.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7.x86_64 (base)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-storage-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-storage-4.5.0-10.el7_6.3.x86_64 (upda

Re: [CentOS-virt] Upgrade to CentOS 7.6 with centos-xen-48 enabled

[Gennardy Smith]

Just to answer my own question, I solved this by installing 
yum-plugin-priorities

and setting priority=10 to centos-virt-xen-48 repository.

Yum doesn't consider the libvirt packages from CentOS base/updates anymore
after this.

Sorry for the noise,

Gennardy

On 23.12.18 11:01, Gennardy Smith wrote:

Hi all,

I'm unable to upgrade my Dom-0 from CentOS 7.5 to CentOS 7.6 with the 
sigvirt

centos-xen-48 repository enabled and Xen components enabled.

It breaks down to down to the fact that 7.6 has a newer version of 
libvirt

included (4.5), while the Xen repository's packages are build against 4.1
version of libvirt.

I also tried to enable the libvirt-latest repository, but that does not
contain libvirt-daemon-driver-xen package, so dependency resolution is
broken again.

Is there some workaround for this, or do I just have to wait for the Xen
repository to be updated? Has someone resolved this problem?

Regards,
G.

The following is the output of yum when running yum update:

[user@dom0 ~]$ sudo yum update
[...]
--> Finished Dependency Resolution
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-driver-libxl-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-network-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-network-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-network = 3.2.1-480.el7
   Available: 
libvirt-daemon-driver-network-4.5.0-10.el7.x86_64 (base)

   libvirt-daemon-driver-network = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon = 4.1.0-2.xen48.el7
   Removing: libvirt-daemon-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon = 4.1.0-2.xen48.el7
   Updated By: libvirt-daemon-4.5.0-10.el7_6.3.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.3
   Available: libvirt-daemon-3.2.1-480.el7.x86_64 
(centos-virt-xen-48)

   libvirt-daemon = 3.2.1-480.el7
   Available: libvirt-daemon-4.5.0-10.el7.x86_64 (base)
   libvirt-daemon = 4.5.0-10.el7
   Available: libvirt-daemon-4.5.0-10.el7_6.2.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-nwfilter-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-nwfilter-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 3.2.1-480.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7.x86_64 (base)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-storage-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-storage-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-storage = 4.

[CentOS-virt] Upgrade to CentOS 7.6 with centos-xen-48 enabled

[Gennardy Smith]

Hi all,

I'm unable to upgrade my Dom-0 from CentOS 7.5 to CentOS 7.6 with the 
sigvirt

centos-xen-48 repository enabled and Xen components enabled.

It breaks down to down to the fact that 7.6 has a newer version of libvirt
included (4.5), while the Xen repository's packages are build against 4.1
version of libvirt.

I also tried to enable the libvirt-latest repository, but that does not
contain libvirt-daemon-driver-xen package, so dependency resolution is
broken again.

Is there some workaround for this, or do I just have to wait for the Xen
repository to be updated? Has someone resolved this problem?

Regards,
G.

The following is the output of yum when running yum update:

[user@dom0 ~]$ sudo yum update
[...]
--> Finished Dependency Resolution
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-driver-libxl-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Removing: libvirt-libs-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt.so.0(LIBVIRT_PRIVATE_4.1.0)(64bit)
   Updated By: libvirt-libs-4.5.0-10.el7_6.3.x86_64 (updates)
  ~libvirt.so.0(LIBVIRT_PRIVATE_4.5.0)(64bit)
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-network-4.1.0-2.xen48.el7.x86_64 (@centos-virt-xen-48)

   libvirt-daemon-driver-network = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-network-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-network = 3.2.1-480.el7
   Available: libvirt-daemon-driver-network-4.5.0-10.el7.x86_64 
(base)

   libvirt-daemon-driver-network = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-network-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-network = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-driver-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon = 4.1.0-2.xen48.el7
   Removing: libvirt-daemon-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon = 4.1.0-2.xen48.el7
   Updated By: libvirt-daemon-4.5.0-10.el7_6.3.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.3
   Available: libvirt-daemon-3.2.1-480.el7.x86_64 
(centos-virt-xen-48)

   libvirt-daemon = 3.2.1-480.el7
   Available: libvirt-daemon-4.5.0-10.el7.x86_64 (base)
   libvirt-daemon = 4.5.0-10.el7
   Available: libvirt-daemon-4.5.0-10.el7_6.2.x86_64 (updates)
   libvirt-daemon = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-nwfilter-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-nwfilter-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-nwfilter = 3.2.1-480.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7.x86_64 (base)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7
   Available: 
libvirt-daemon-driver-nwfilter-4.5.0-10.el7_6.2.x86_64 (updates)

   libvirt-daemon-driver-nwfilter = 4.5.0-10.el7_6.2
Error: Package: libvirt-daemon-xen-4.1.0-2.xen48.el7.x86_64 
(@centos-virt-xen-48)

   Requires: libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Removing: 
libvirt-daemon-driver-storage-4.1.0-2.xen48.el7.x86_64 (@centos-virt-xen-48)

   libvirt-daemon-driver-storage = 4.1.0-2.xen48.el7
   Updated By: 
libvirt-daemon-driver-storage-4.5.0-10.el7_6.3.x86_64 (updates)

   libvirt-daemon-driver-storage = 4.5.0-10.el7_6.3
   Available: 
libvirt-daemon-driver-storage-3.2.1-480.el7.x86_64 (centos-virt-xen-48)

   libvirt-daemon-driver-storage = 3.2.1-480.el7
   Available: libvirt-daemon-driver-storage-4.5.0-10.el7.x86_64 
(base)

   libvirt-daemon-driver-storage = 4.5.0-10.

Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[John Naggets]

Hi Chris,

For completeness just wanted to mention that it is the first time I
see in newer servers that it is not possible to PXE boot from the
network using legacy mode (BIOS). It seems like the NICs are missing
the required piece of code for that as all 4 NICs of that server fail
to boot legacy PXE with the following message:

!PXE structure was not found in UNDI driver code segment.

Best,
J.

On Wed, Jan 31, 2018 at 9:06 PM, Chris Adams  wrote:
> Once upon a time, John Naggets  said:
>> Jonathan brings it exactly to the point: we have to face UEFI because
>> legacy mode is fading out, if I enable legacy mode I can't even boot
>> anymore through the network (PXE) as these newer network cards can
>> only boot PXE with UEFI.
>
> UEFI PXE is different than BIOS PXE and needs to download different
> software from the TFTP server.  I use syslinux for BIOS PXE, but it
> doesn't seem to work with UEFI PXE so I use grub2 (I use the secure boot
> shim from Fedora to support as many setups as practical).  You can have
> both available at the same time (takes a DHCP tweak).
>
> Just like the early days of BIOS PXE however, UEFI PXE clients don't
> always seem to do the right thing.  I have an Intel NUC (7th gen), and
> it always fails with UEFI PXE.
>
> --
> Chris Adams 
> ___
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Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[Chris Adams]

Once upon a time, John Naggets  said:
> Jonathan brings it exactly to the point: we have to face UEFI because
> legacy mode is fading out, if I enable legacy mode I can't even boot
> anymore through the network (PXE) as these newer network cards can
> only boot PXE with UEFI.

UEFI PXE is different than BIOS PXE and needs to download different
software from the TFTP server.  I use syslinux for BIOS PXE, but it
doesn't seem to work with UEFI PXE so I use grub2 (I use the secure boot
shim from Fedora to support as many setups as practical).  You can have
both available at the same time (takes a DHCP tweak).

Just like the early days of BIOS PXE however, UEFI PXE clients don't
always seem to do the right thing.  I have an Intel NUC (7th gen), and
it always fails with UEFI PXE.

-- 
Chris Adams 
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Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[John Naggets]

I checked and secure boot is turned off.

Jonathan brings it exactly to the point: we have to face UEFI because
legacy mode is fading out, if I enable legacy mode I can't even boot
anymore through the network (PXE) as these newer network cards can
only boot PXE with UEFI.

In the mean time I have installed Ubuntu 17.10 with Xen and I was
lucky to see that this combination works with UEFI even Xen.


On Wed, Jan 31, 2018 at 2:12 PM, Johnny Hughes  wrote:
> On 01/30/2018 04:23 PM, John Naggets wrote:
>> Hi,
>>
>> I installed CentOS 7.4 on a modern Lenovo ThinkSystem SR630 server
>> which uses UEFI. So far so good CentOS 7.4 works fine so then I went
>> on to install the Xen hypervisor by following the instructions from
>> the wiki (https://wiki.centos.org/HowTos/Xen/Xen4QuickStart).
>>
>> Unfortunately when I reboot after having installed the xen package the
>> system does not boot into "CentOS Linux, with Xen hypervisor" from the
>> grub menu prompt. I get the following error:
>>
>> Loading Xen 4.6.6-8.el7 ...
>> error: can't find command `multiboot'.
>> Loading Linux 4.9.75-29.el7.x86_64 ...
>> error: can't find command `module'.
>> Loading initial ramdisk ...
>> error: can't find command `module'.
>>
>> Press any key to continue...
>>
>> The problem which I encounter here is exactly the same issue as
>> described for Fedora in the RedHat bugs:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1286317 with the exception
>> that for me it's CentOS 7.4 and that the workarounds as described in
>> that bug do not work.
>>
>> Does anyone know how I can make my CentOS boot with the Xen hypervisor
>> using UEFI?
>>
>> Thank you very much for your help.
>>
>
> Usually not an issue with UEFI .. but with Secure Boot
>
> You need to make sure Secure Boot is off.  It is sometimes called Legacy
> Booting turned on, etc.
>
>
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Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[Jonathan Billings]

On Tue, Jan 30, 2018 at 11:51:48PM +, Mikhail Utin wrote:
> Why do you need UEFI? It does not add to security "a lot" but was
> designed to block booting software like a "hypervisor". I used my
> Dell notebooks to test our hypervisor identification software
> (HyperCatcher if you are interested) which is bootable
> image. However, I was unable to boot it until I disabled UEFI. As I
> understand it, it will block anything from booting excepting
> original OS. Your Xen and our HyperCatcher are outsiders for UEFI. 

You're thinking of Secure Boot, not all of UEFI.

For what its worth, UEFI is what we're stuck with, all modern hardware
uses it (and legacy boot is just a special UEFI bootloader).  Intel
plans to phase out the legacy bootloader in future releases of their
chipsets as well, so it wouldn't hurt to learn how to use UEFI.

-- 
Jonathan Billings 
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Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[Johnny Hughes]

On 01/30/2018 04:23 PM, John Naggets wrote:
> Hi,
> 
> I installed CentOS 7.4 on a modern Lenovo ThinkSystem SR630 server
> which uses UEFI. So far so good CentOS 7.4 works fine so then I went
> on to install the Xen hypervisor by following the instructions from
> the wiki (https://wiki.centos.org/HowTos/Xen/Xen4QuickStart).
> 
> Unfortunately when I reboot after having installed the xen package the
> system does not boot into "CentOS Linux, with Xen hypervisor" from the
> grub menu prompt. I get the following error:
> 
> Loading Xen 4.6.6-8.el7 ...
> error: can't find command `multiboot'.
> Loading Linux 4.9.75-29.el7.x86_64 ...
> error: can't find command `module'.
> Loading initial ramdisk ...
> error: can't find command `module'.
> 
> Press any key to continue...
> 
> The problem which I encounter here is exactly the same issue as
> described for Fedora in the RedHat bugs:
> https://bugzilla.redhat.com/show_bug.cgi?id=1286317 with the exception
> that for me it's CentOS 7.4 and that the workarounds as described in
> that bug do not work.
> 
> Does anyone know how I can make my CentOS boot with the Xen hypervisor
> using UEFI?
> 
> Thank you very much for your help.
> 

Usually not an issue with UEFI .. but with Secure Boot

You need to make sure Secure Boot is off.  It is sometimes called Legacy
Booting turned on, etc.



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Re: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[Mikhail Utin]

Why do you need UEFI? It does not add to security "a lot" but was designed to 
block booting software like a "hypervisor". I used my Dell notebooks to test 
our hypervisor identification software (HyperCatcher if you are interested) 
which is bootable image. However, I was unable to boot it until I disabled 
UEFI. As I understand it, it will block anything from booting excepting 
original OS. Your Xen and our HyperCatcher are outsiders for UEFI.


Mikhail Utin



From: CentOS <centos-boun...@centos.org> on behalf of John Naggets 
<hostingnugg...@gmail.com>
Sent: Tuesday, January 30, 2018 17:23
To: centos@centos.org
Subject: [CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not 
booting from grub

Hi,

I installed CentOS 7.4 on a modern Lenovo ThinkSystem SR630 server
which uses UEFI. So far so good CentOS 7.4 works fine so then I went
on to install the Xen hypervisor by following the instructions from
the wiki (https://wiki.centos.org/HowTos/Xen/Xen4QuickStart).
HowTos/Xen/Xen4QuickStart - CentOS 
Wiki<https://wiki.centos.org/HowTos/Xen/Xen4QuickStart>
wiki.centos.org
Scope. This guide will help you get from a baseline CentOS/x86_64 install to 
running the complete Xen-4 stack in just under 10 minutes, this includes 
getting your ...




Unfortunately when I reboot after having installed the xen package the
system does not boot into "CentOS Linux, with Xen hypervisor" from the
grub menu prompt. I get the following error:

Loading Xen 4.6.6-8.el7 ...
error: can't find command `multiboot'.
Loading Linux 4.9.75-29.el7.x86_64 ...
error: can't find command `module'.
Loading initial ramdisk ...
error: can't find command `module'.

Press any key to continue...

The problem which I encounter here is exactly the same issue as
described for Fedora in the RedHat bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=1286317 with the exception
With 4.5.2 Xen update, the system no longer boot - Red 
Hat<https://bugzilla.redhat.com/show_bug.cgi?id=1286317>
bugzilla.redhat.com
Red Hat Bugzilla – Bug 1286317. With 4.5.2 Xen update, the system no longer 
boot. Last modified: 2017-08-08 19:49:12 EDT



that for me it's CentOS 7.4 and that the workarounds as described in
that bug do not work.

Does anyone know how I can make my CentOS boot with the Xen hypervisor
using UEFI?

Thank you very much for your help.

Best regards,
John
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[CentOS] Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

[John Naggets]

Hi,

I installed CentOS 7.4 on a modern Lenovo ThinkSystem SR630 server
which uses UEFI. So far so good CentOS 7.4 works fine so then I went
on to install the Xen hypervisor by following the instructions from
the wiki (https://wiki.centos.org/HowTos/Xen/Xen4QuickStart).

Unfortunately when I reboot after having installed the xen package the
system does not boot into "CentOS Linux, with Xen hypervisor" from the
grub menu prompt. I get the following error:

Loading Xen 4.6.6-8.el7 ...
error: can't find command `multiboot'.
Loading Linux 4.9.75-29.el7.x86_64 ...
error: can't find command `module'.
Loading initial ramdisk ...
error: can't find command `module'.

Press any key to continue...

The problem which I encounter here is exactly the same issue as
described for Fedora in the RedHat bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=1286317 with the exception
that for me it's CentOS 7.4 and that the workarounds as described in
that bug do not work.

Does anyone know how I can make my CentOS boot with the Xen hypervisor
using UEFI?

Thank you very much for your help.

Best regards,
John
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[CentOS] Xen PV DomU's and the 3.10.0-693.el7 Kernel

[Johnny Hughes]

If you are running CentOS Linux 7 inside a Xen DomU (VM) in PV mode, you
can not upgrade to the standard 7.4.1708 kernel that is currently in the
CR repo and that will be soon released in our file 7.4.1708 tree
(3.10.0-693.*el7)

The CentOS Plus kernel will be available when we release the 7.4.1708
tree and it does boot inside a Xen DomU PV, so you can either upgrade to
the CentOS Plus kernel in PV mode .. or you can shift your DomU to
either HVM or PVHVM modes.  PVHVM is more like PV mode, and is usually
much better than HVM mode.

More info on PVHVM here:
https://wiki.xen.org/wiki/PV_on_HVM

https://wiki.xen.org/wiki/Xen_Linux_PV_on_HVM_drivers

The anaconda installer and pxe booting from the standard tree 7.4.1708
tree will also not work in PV mode for new installs, only PVHVM or HVM
installs can be done with the 7.4.1708 tree.

Note:  This is an upstream source code issue and will not be fixed in
the main CentOS Linux 7 kernel unless it is fixed upstream in the RHEL
source code.

We are sorry for any inconvenience this issue may cause.
Thanks,
Johnny Hughes




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[CentOS] Xen-4.4 branch End of Life

[Johnny Hughes]

The CentOS VIrtualization Special Interest Group wants to remind
everyone that the End of Life for the Xen-4.4 branch (currently
4.4.4-19) will be March 31st, 2017.

This is because the Xen Project will no longer support Xen-4.4 after
that date, based on this link:

https://wiki.xenproject.org/wiki/Xen_Project_Release_Features

Xen-4.6 is still available and will be maintained until October 2018 (on
both CentOS-6 and CentOS-7) and Xen-4.8 will be available soon.

Thanks,
Johnny Hughes



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Re: [CentOS-virt] Centos Xen libvirt question

[M.K.Pai]

Hi Chuck,


> Looking for libvirt-daemon-xen for Centos 7.  Does anyone have the
> location of this package?
>
>
Possibly at http://cbs.centos.org/koji/buildinfo?buildID=1348

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People's Commissar for Permanent Revolution
Supreme Director of Party Enlightenment
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Re: [CentOS-virt] Centos Xen libvirt question

[Chuck Meade]

Thanks, got it.

Chuck

On 09/04/2015 05:36 AM, M.K.Pai wrote:
> Hi Chuck,
>
>
> Looking for libvirt-daemon-xen for Centos 7.  Does anyone have the 
> location of this package?
>
>
> Possibly at http://cbs.centos.org/koji/buildinfo?buildID=1348
>
> -- Saint Pai
> Hero of Socialist Labour
> People's Commissar for Permanent Revolution
> Supreme Director of Party Enlightenment
>
>  
>
>
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[CentOS-virt] Centos Xen libvirt question

[Chuck Meade]

Hello,

Looking for libvirt-daemon-xen for Centos 7.  Does anyone have the location of 
this package?

Thanks,
Chuck
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Grant McWilliams]

On Mon, Mar 16, 2015 at 10:32 PM, Nico Kadel-Garcia nka...@gmail.com
wrote:

 On Mon, Mar 16, 2015 at 4:02 AM, Manuel Wolfshant
 wo...@nobugconsulting.ro wrote:

  Quote from an actual installation:
 
  [root@xenh4 ~]# history| grep virt
  virt-install  -n dhcpdns -p -r 1024 --os-type=linux --vnc -f
  /var/lib/xen/images/dhcpdns -s 2 -l
  http://192.168.50.40/mrepo/centos6-i386/disc1 -x
  ks=ftp://192.168.50.40/linux/ks-minimalC6-xen.cfg;
 
  [root@xenh4 ~]# uname -a
  Linux xenh4 2.6.18-400.1.1.el5xen #1 SMP Thu Dec 18 02:18:37 EST 2014
 i686
  i686 i386 GNU/Linux
 
 
 https://github.com/CentOS/Community-Kickstarts/blob/master/ks-minimalC6.cfg
  is quite close to the above mentioned ks-minimalC6-xen.cfg ( actually
 both
  are descendants of the same template of mine )

 Thanks The key, hinted at by various notes in this thread, was the
 use of the --location to point to a network accessibleinstallation
 repository. I'm afraid that the Xen wiki directions about --location
 are a bit unclear about the need for this to be the base of a
 deployment directory, one that *must* have a working subdirectory
 called 'imagex/xen' with the relevant files in it. I admint, I have to
 just love hardcoded, hidden requirements!!!

 I'll point out for others who may need to image systems quickly that
 it's often more effective, especially in terms of speed and external
 bandwidth, to use an internal mirror as you did. I'll also point out
 that it can be awfully handy to keep such a mirror up-to-date and use
 it your local configurations. I publish such scripts at
 https://github.com/nkadel/nkadel-rsync-scripts, in case anyone else
 wants them.

 I'll also mention my old habit in ks.cfg files of doing this, to hang
 onto the actual ks.cfg instead of the confused and '%pre' and '%post'
 stripped, anaconda reverse engineered oddness in
 /root/anaconda-ks.cfg.

 %pre
  cp -f /tmp/ks.cfg /mnt/sysimage/root/ks.cfg
 %end
 ___


Nico,
   I wrote tutorials on how to do this when I was using xen. I haven't used
these tutorials in a couple of years but they worked then so they should
still work now.  This is for an automated CentOS 6 (x86_64).

http://grantmcwilliams.com/item/538-centos-6-virtual-machine-64-bit-installation-on-xen

Grant McWilliams
http://grantmcwilliams.com/

Some people, when confronted with a problem, think I know, I'll use
Windows.
Now they have two problems.
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

On Wed, Mar 18, 2015 at 9:11 PM, Grant McWilliams
grantmasterfl...@gmail.com wrote:

 Nico,
I wrote tutorials on how to do this when I was using xen. I haven't used
 these tutorials in a couple of years but they worked then so they should
 still work now.  This is for an automated CentOS 6 (x86_64).

 http://grantmcwilliams.com/item/538-centos-6-virtual-machine-64-bit-installation-on-xen

 Grant McWilliams
 http://grantmcwilliams.com/

I'm reading your notes. They're not bad, but they make me nervous in a
number of ways.

* VM's should *always* be assigned stable, but unique MAC's for the
network devices. This prevents the udev settings, and tendency of
tools like NetworkManager and anaconda from being unable to configure
network devices that they've stored hard-coded MAC addresses for.
There is *no* GUI or built-in command line tool for clearing these,
you have to do it by hand. There are various ways to deal with this,
but allowing the virt-install or similar tools to assign a MAC *once*
and then locking it down in the config file is quite effective.

Pre-planning your MAC addresses also allows DHCP reservations to be
configured, very useful for PXE setups and stabilizing your DNS and
firewall configuraitons.

* Don't install rpmforge anymore by default: it's effectively moribund
since Dag Weiers moved on to other projects, and isn't getting
updates. You can now install EPEL with 'yum install epel-release, and
unless you need tools that overlap with CentOS tools it's much safer.
(I wrote the last few subversion RPM's for RPMforge, and have been
waiting way too long for updates to be accepted.)

* Frankly, the use of 'virt-install' with a --location setting to
point to the online kernels from a relevant source repository, and
some options to select a disk image size,  seems to skip gracefully
over all the manually build your disk image and manually edit your
/etc/xen/[config] file..


 Some people, when confronted with a problem, think I know, I'll use
 Windows.
 Now they have two problems.


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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

On Mon, Mar 16, 2015 at 4:02 AM, Manuel Wolfshant
wo...@nobugconsulting.ro wrote:

 Quote from an actual installation:

 [root@xenh4 ~]# history| grep virt
 virt-install  -n dhcpdns -p -r 1024 --os-type=linux --vnc -f
 /var/lib/xen/images/dhcpdns -s 2 -l
 http://192.168.50.40/mrepo/centos6-i386/disc1 -x
 ks=ftp://192.168.50.40/linux/ks-minimalC6-xen.cfg;

 [root@xenh4 ~]# uname -a
 Linux xenh4 2.6.18-400.1.1.el5xen #1 SMP Thu Dec 18 02:18:37 EST 2014 i686
 i686 i386 GNU/Linux

 https://github.com/CentOS/Community-Kickstarts/blob/master/ks-minimalC6.cfg
 is quite close to the above mentioned ks-minimalC6-xen.cfg ( actually both
 are descendants of the same template of mine )

Thanks The key, hinted at by various notes in this thread, was the
use of the --location to point to a network accessibleinstallation
repository. I'm afraid that the Xen wiki directions about --location
are a bit unclear about the need for this to be the base of a
deployment directory, one that *must* have a working subdirectory
called 'imagex/xen' with the relevant files in it. I admint, I have to
just love hardcoded, hidden requirements!!!

I'll point out for others who may need to image systems quickly that
it's often more effective, especially in terms of speed and external
bandwidth, to use an internal mirror as you did. I'll also point out
that it can be awfully handy to keep such a mirror up-to-date and use
it your local configurations. I publish such scripts at
https://github.com/nkadel/nkadel-rsync-scripts, in case anyone else
wants them.

I'll also mention my old habit in ks.cfg files of doing this, to hang
onto the actual ks.cfg instead of the confused and '%pre' and '%post'
stripped, anaconda reverse engineered oddness in
/root/anaconda-ks.cfg.

%pre
 cp -f /tmp/ks.cfg /mnt/sysimage/root/ks.cfg
%end
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Pasi Kärkkäinen]

On Sun, Mar 15, 2015 at 07:52:42PM -0700, Sarah Newman wrote:
  
  I'd really prefer to work from 'virsh' than from hand-writing xl
  configuration files.When I last did this sort of thing, I worked from
  a PXE environment that I controlled and could reserve DHCP settings
  based on MAC addresses, and tune PXE to boot from disk by default but
  allow users to select a clean re-install of the operating system they
  wanted.
 
 virt-install with --location maybe? Never tried it but it looks like what you 
 want.
 
 http://linux.die.net/man/1/virt-install
 

Yeah you can use virt-install on CentOS 5 Xen host to install CentOS 6 PV domUs,
I do that often, an example for GUI installation:

virt-install -d -n vmname -r 1024 --vcpus=2 -f /dev/vg01/vmname_disk0 -b virbr0 
--vnc -p -l http://ftp.funet.fi/pub/mirrors/centos.org/6.5/os/x86_64;

(you need to have virt-viewer installed, that'll be used to display the VNC GUI 
console).

-- Pasi

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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Manuel Wolfshant]

On 03/16/2015 08:58 AM, Pasi Kärkkäinen wrote:

On Sun, Mar 15, 2015 at 07:52:42PM -0700, Sarah Newman wrote:

I'd really prefer to work from 'virsh' than from hand-writing xl
configuration files.When I last did this sort of thing, I worked from
a PXE environment that I controlled and could reserve DHCP settings
based on MAC addresses, and tune PXE to boot from disk by default but
allow users to select a clean re-install of the operating system they
wanted.

virt-install with --location maybe? Never tried it but it looks like what you 
want.

http://linux.die.net/man/1/virt-install


Yeah you can use virt-install on CentOS 5 Xen host to install CentOS 6 PV domUs,
I do that often, an example for GUI installation:

virt-install -d -n vmname -r 1024 --vcpus=2 -f /dev/vg01/vmname_disk0 -b virbr0 --vnc -p 
-l http://ftp.funet.fi/pub/mirrors/centos.org/6.5/os/x86_64;

(you need to have virt-viewer installed, that'll be used to display the VNC GUI 
console).

-- Pasi


Quote from an actual installation:

[root@xenh4 ~]# history| grep virt
virt-install  -n dhcpdns -p -r 1024 --os-type=linux --vnc -f 
/var/lib/xen/images/dhcpdns -s 2 -l 
http://192.168.50.40/mrepo/centos6-i386/disc1 -x 
ks=ftp://192.168.50.40/linux/ks-minimalC6-xen.cfg;


[root@xenh4 ~]# uname -a
Linux xenh4 2.6.18-400.1.1.el5xen #1 SMP Thu Dec 18 02:18:37 EST 2014 
i686 i686 i386 GNU/Linux


https://github.com/CentOS/Community-Kickstarts/blob/master/ks-minimalC6.cfg 
is quite close to the above mentioned ks-minimalC6-xen.cfg ( actually 
both are descendants of the same template of mine )


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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Pasi Kärkkäinen]

On Thu, Mar 12, 2015 at 10:34:39PM -0400, Nico Kadel-Garcia wrote:
 I'm looking at a CentOS 5  Xen server that I'd really like to put some
 more recent VM's. There are reasons not to touch it at the moment, so
 I can't upgrade it in place today.
 
 Has anyone successfully installed a CentOS 6 VM, paravirtualized, on a
 CentOS 5 Xen server , without significant Xen upgrades? If so, can I
 get a copy from a reputable source, or one that I can review before
 using? I'm having a bit of difficulty arranging a PXE enironment to do
 a paraviirtualized installation with, and there are apparently
 difficulties doing a paravirtualzed system with CD or DVD installation
 with Xen.
 
   Nico Kadel-Garcia nka...@gmail.com

Yep, CentOS 6 VMs run just fine on CentOS 5 Xen host.

-- Pasi


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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Peter]

On 03/16/2015 11:25 AM, Nico Kadel-Garcia wrote:
 I've got CentOS VM's running fine, and have done them before. But
 previously, I deployed the same base OS on the VM as on the Xen
 server, so paravirtualization posed few risks. And I had control of
 the DHCP setup. so I could trivially set up a tftp server to do a
 non-CD installation, because Xen, at last look, doesn't support
 installing a paravirtualized host from a CD image.

It does as long as (1) the kernel has Xen PV support (CentOS 6 standard
kernel does) and (2) it has the necessary drivers in the initrd (I think
this is where the CD image is lacking), then you should, in theory, be
able to pv-grub boot to the CD.  Alternatively you can boot to the CD on
another box first, copy the kernel off to a USB stick, and generate a
new initrd with the xen drivers included, then put those on the Xen host
and boot to the VM CD image using those in the kernel= and initrd= lines
in the domain.cfg file.

The other way is to boot to the CD as an HVM domain and install, then
convert it to a PV domain afterwards, which is not all that difficult to do.

There is a third way which involves using yum to install the @core group
plus kernel to an image, then tweak and boot to that as a PV domain.
This is how I have done it in the past.

 So I'm right back to my effectively unanswered original questions. So
 please: I asked a very specific pair of questions, and they remain
 unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
 to call it this week): Does CentOS 6 work, paravirtualized, on such a
 server?

Yes, I have done that until I upgraded the CentOS 5 host to CentOS 6 a
couple years ago.

 And given my deployment issues, does anyone have a base OS
 image I can get a copy of?

Sorry my image templates that I use are highly customized for my own
work, but I have told you three different ways to accomplish it above.


Peter
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

On Sun, Mar 15, 2015 at 3:17 PM, Pasi Kärkkäinen pa...@iki.fi wrote:
 On Thu, Mar 12, 2015 at 10:34:39PM -0400, Nico Kadel-Garcia wrote:
 I'm looking at a CentOS 5  Xen server that I'd really like to put some
 more recent VM's. There are reasons not to touch it at the moment, so
 I can't upgrade it in place today.

 Has anyone successfully installed a CentOS 6 VM, paravirtualized, on a
 CentOS 5 Xen server , without significant Xen upgrades? If so, can I
 get a copy from a reputable source, or one that I can review before
 using? I'm having a bit of difficulty arranging a PXE enironment to do
 a paraviirtualized installation with, and there are apparently
 difficulties doing a paravirtualzed system with CD or DVD installation
 with Xen.

   Nico Kadel-Garcia nka...@gmail.com

 Yep, CentOS 6 VMs run just fine on CentOS 5 Xen host.

I've got CentOS VM's running fine, and have done them before. But
previously, I deployed the same base OS on the VM as on the Xen
server, so paravirtualization posed few risks. And I had control of
the DHCP setup. so I could trivially set up a tftp server to do a
non-CD installation, because Xen, at last look, doesn't support
installing a paravirtualized host from a CD image.

So I'm right back to my effectively unanswered original questions. So
please: I asked a very specific pair of questions, and they remain
unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
to call it this week): Does CentOS 6 work, paravirtualized, on such a
server? And given my deployment issues, does anyone have a base OS
image I can get a copy of?
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Sarah Newman]

On 03/15/2015 03:25 PM, Nico Kadel-Garcia wrote:
 So I'm right back to my effectively unanswered original questions. So
 please: I asked a very specific pair of questions, and they remain
 unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
 to call it this week): Does CentOS 6 work, paravirtualized, on such a
 server? And given my deployment issues, does anyone have a base OS
 image I can get a copy of?

I'm not sure why you need tftp to do a net install assuming you control the 
guest configuration.

How about

kernel = file from 
https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/vmlinuz
ramdisk = file from 
https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/initrd.img
extra = console=hvc0
memory = 512 or larger

--Sarah
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Sarah Newman]

On 03/15/2015 07:39 PM, Nico Kadel-Garcia wrote:
 On Sun, Mar 15, 2015 at 8:26 PM, Sarah Newman s...@prgmr.com wrote:
 On 03/15/2015 03:25 PM, Nico Kadel-Garcia wrote:
 So I'm right back to my effectively unanswered original questions. So
 please: I asked a very specific pair of questions, and they remain
 unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
 to call it this week): Does CentOS 6 work, paravirtualized, on such a
 server? And given my deployment issues, does anyone have a base OS
 image I can get a copy of?

 I'm not sure why you need tftp to do a net install assuming you control the 
 guest configuration.

 How about

 kernel = file from 
 https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/vmlinuz
 ramdisk = file from 
 https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/initrd.img
 extra = console=hvc0
 memory = 512 or larger

 --Sarah
 
 I'll be happy to try this. Thank you for the pointer. Are you
 confident that 'console=hvc0' is the right installation time message
 for this? And will I be able to access a CD or DVD image for actual OS
 installation with these options?

It is net install IE you download packages over the network. No CD/DVD.

console=hvc0 is the xen part, otherwise look at the standard installation 
instructions for centos 6.

 
 I'd really prefer to work from 'virsh' than from hand-writing xl
 configuration files.When I last did this sort of thing, I worked from
 a PXE environment that I controlled and could reserve DHCP settings
 based on MAC addresses, and tune PXE to boot from disk by default but
 allow users to select a clean re-install of the operating system they
 wanted.

virt-install with --location maybe? Never tried it but it looks like what you 
want.

http://linux.die.net/man/1/virt-install



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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

On Sun, Mar 15, 2015 at 8:26 PM, Sarah Newman s...@prgmr.com wrote:
 On 03/15/2015 03:25 PM, Nico Kadel-Garcia wrote:
 So I'm right back to my effectively unanswered original questions. So
 please: I asked a very specific pair of questions, and they remain
 unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
 to call it this week): Does CentOS 6 work, paravirtualized, on such a
 server? And given my deployment issues, does anyone have a base OS
 image I can get a copy of?

 I'm not sure why you need tftp to do a net install assuming you control the 
 guest configuration.

 How about

 kernel = file from 
 https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/vmlinuz
 ramdisk = file from 
 https://mirrors.kernel.org/centos/6/os/i386/images/pxeboot/initrd.img
 extra = console=hvc0
 memory = 512 or larger

 --Sarah

I'll be happy to try this. Thank you for the pointer. Are you
confident that 'console=hvc0' is the right installation time message
for this? And will I be able to access a CD or DVD image for actual OS
installation with these options?

I'd really prefer to work from 'virsh' than from hand-writing xl
configuration files.When I last did this sort of thing, I worked from
a PXE environment that I controlled and could reserve DHCP settings
based on MAC addresses, and tune PXE to boot from disk by default but
allow users to select a clean re-install of the operating system they
wanted.
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Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

On Sun, Mar 15, 2015 at 8:11 PM, Peter pe...@pajamian.dhs.org wrote:
 On 03/16/2015 11:25 AM, Nico Kadel-Garcia wrote:
 I've got CentOS VM's running fine, and have done them before. But
 previously, I deployed the same base OS on the VM as on the Xen
 server, so paravirtualization posed few risks. And I had control of
 the DHCP setup. so I could trivially set up a tftp server to do a
 non-CD installation, because Xen, at last look, doesn't support
 installing a paravirtualized host from a CD image.

 It does as long as (1) the kernel has Xen PV support (CentOS 6 standard
 kernel does) and (2) it has the necessary drivers in the initrd (I think
 this is where the CD image is lacking), then you should, in theory, be
 able to pv-grub boot to the CD.  Alternatively you can boot to the CD on

Not according to the Xen guidelines I was finding. If they're
incorrect, *for a CentOS 5 Xen hypervisor*, I'd love to be able to use
that. Unfortunately, one of the banes of my technology existence is
when people say that works great! and just look on Google,!, and
the answer they vaguely remember does not actually include the
situation I desdcribed.

 another box first, copy the kernel off to a USB stick, and generate a
 new initrd with the xen drivers included, then put those on the Xen host
 and boot to the VM CD image using those in the kernel= and initrd= lines
 in the domain.cfg file.

Ouch. I've hand-modified CD and DVD images in the past, it's a pain
the neck, It's been compunded by the insistece that the  compressed
vmlinuz file is, itself, named vmlinuz instead of vmlinuz.gz,
which always struck me as fairly nutty.

 The other way is to boot to the CD as an HVM domain and install, then
 convert it to a PV domain afterwards, which is not all that difficult to do.

This would probably be safest for me right now, since I have a
testable HVM instance of CentOS 6 to copy and work with. I'm not
finding any good guidelines for migrating from HVM to
paravirtualizaton for old Xen environments. Have you seen any, or done
this process? The notes I find often include extraneous and hopefully
unnecessary steps, such as http://support.citrix.com/article/CTX121875
saying. It's legible, but leaves out the kind of incompatibility
issues that I;ve been concerned about hopping from a Xen server on
CentOS 5.x to a CentOS 6.x guest.

 There is a third way which involves using yum to install the @core group
 plus kernel to an image, then tweak and boot to that as a PV domain.
 This is how I have done it in the past.

I'm sorry, but what? Are you building a chroot cage yourself, such as
using 'mock', or are you starting with someone else's working
para-virtualized image? (See my notes above).

 So I'm right back to my effectively unanswered original questions. So
 please: I asked a very specific pair of questions, and they remain
 unanswered. CentOS 5 Xen server (hypervisor, or Dom0, whatever we want
 to call it this week): Does CentOS 6 work, paravirtualized, on such a
 server?

 Yes, I have done that until I upgraded the CentOS 5 host to CentOS 6 a
 couple years ago.

Thanks! THAT is one of the questions I really wanted an answer for.

 And given my deployment issues, does anyone have a base OS
 image I can get a copy of?

 Sorry my image templates that I use are highly customized for my own
 work, but I have told you three different ways to accomplish it above.

Well, dang!
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[CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server

[Nico Kadel-Garcia]

I'm looking at a CentOS 5  Xen server that I'd really like to put some
more recent VM's. There are reasons not to touch it at the moment, so
I can't upgrade it in place today.

Has anyone successfully installed a CentOS 6 VM, paravirtualized, on a
CentOS 5 Xen server , without significant Xen upgrades? If so, can I
get a copy from a reputable source, or one that I can review before
using? I'm having a bit of difficulty arranging a PXE enironment to do
a paraviirtualized installation with, and there are apparently
difficulties doing a paravirtualzed system with CD or DVD installation
with Xen.

  Nico Kadel-Garcia nka...@gmail.com
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[CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps

[Mike McClurg]

Hi list,

Dave Scott has been working on a prototype of XenServer's Xapi running 
on stock CentOS 6.4 x86_64, with libvirt and ceph integration. He plans 
to demo this at the CentOS dojo in Aldershot next week.

We'll be publishing the RPMs for this in a public Yum repo, and we would 
really like for these RPMs to eventually live in the xen-c6 repo. I was 
wondering what are the steps for making this happen, and also if it 
would be possible to make this happen before the dojo next Friday (12 July).

We can provide a public Yum repository with these SRPMS and RPMS, if 
that would help. Thanks,

Mike
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Re: [CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps

[Dave Scott]

Hi,

Thanks Mike for bringing this up.

On Jul 2, 2013, at 6:15 PM, Mike McClurg mike.mccl...@citrix.com wrote:

 Hi list,
 
 Dave Scott has been working on a prototype of XenServer's Xapi running 
 on stock CentOS 6.4 x86_64, with libvirt and ceph integration. He plans 
 to demo this at the CentOS dojo in Aldershot next week.
 
 We'll be publishing the RPMs for this in a public Yum repo, and we would 
 really like for these RPMs to eventually live in the xen-c6 repo. I was 
 wondering what are the steps for making this happen, and also if it 
 would be possible to make this happen before the dojo next Friday (12 July).

My RPMS are in a bit of an experimental state, and I'd really appreciate 
people's feedback. It might be too soon to merge them into xen-c6 by next week, 
but it would be nice if I could point people at an online copy somewhere. 
Perhaps we could make a xen-c6-experimental repo or something? I could then 
rsync new builds regularly and put setup instructions on the CentOS wiki.

Cheers,
Dave


 
 We can provide a public Yum repository with these SRPMS and RPMS, if 
 that would help. Thanks,
 
 Mike
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Re: [CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps

[Grant McWilliams]

I'd like to test them as soon as you get ANY repo up.

Grant McWilliams
http://grantmcwilliams.com/

Some people, when confronted with a problem, think I know, I'll use
Windows.
Now they have two problems.


On Tue, Jul 2, 2013 at 11:23 AM, Dave Scott dave.sc...@eu.citrix.comwrote:

 Hi,

 Thanks Mike for bringing this up.

 On Jul 2, 2013, at 6:15 PM, Mike McClurg mike.mccl...@citrix.com
 wrote:

  Hi list,
 
  Dave Scott has been working on a prototype of XenServer's Xapi running
  on stock CentOS 6.4 x86_64, with libvirt and ceph integration. He plans
  to demo this at the CentOS dojo in Aldershot next week.
 
  We'll be publishing the RPMs for this in a public Yum repo, and we would
  really like for these RPMs to eventually live in the xen-c6 repo. I was
  wondering what are the steps for making this happen, and also if it
  would be possible to make this happen before the dojo next Friday (12
 July).

 My RPMS are in a bit of an experimental state, and I'd really appreciate
 people's feedback. It might be too soon to merge them into xen-c6 by next
 week, but it would be nice if I could point people at an online copy
 somewhere. Perhaps we could make a xen-c6-experimental repo or something? I
 could then rsync new builds regularly and put setup instructions on the
 CentOS wiki.

 Cheers,
 Dave


 
  We can provide a public Yum repository with these SRPMS and RPMS, if
  that would help. Thanks,
 
  Mike
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Re: [CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps

[Robert Dinse]

  I operate an ISP, I'd be willing to provide ftp/web space for this if
the bandwidth doesn't become crippling.

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
  Eskimo North Linux Friendly Internet Access, Shell Accounts, and Hosting.
Knowledgeable human assistance, not telephone trees or script readers.
  See our web site: http://www.eskimo.com/ (206) 812-0051 or (800) 246-6874.

On Tue, 2 Jul 2013, Grant McWilliams wrote:

 Date: Tue, 2 Jul 2013 13:24:19 -0600
 From: Grant McWilliams grantmasterfl...@gmail.com
 Reply-To: Discussion about the virtualization on CentOS
 centos-virt@centos.org
 To: Discussion about the virtualization on CentOS centos-virt@centos.org
 Subject: Re: [CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps
 
 I'd like to test them as soon as you get ANY repo up.

 Grant McWilliams
 http://grantmcwilliams.com/

 Some people, when confronted with a problem, think I know, I'll use
 Windows.
 Now they have two problems.


 On Tue, Jul 2, 2013 at 11:23 AM, Dave Scott dave.sc...@eu.citrix.comwrote:

 Hi,

 Thanks Mike for bringing this up.

 On Jul 2, 2013, at 6:15 PM, Mike McClurg mike.mccl...@citrix.com
 wrote:

 Hi list,

 Dave Scott has been working on a prototype of XenServer's Xapi running
 on stock CentOS 6.4 x86_64, with libvirt and ceph integration. He plans
 to demo this at the CentOS dojo in Aldershot next week.

 We'll be publishing the RPMs for this in a public Yum repo, and we would
 really like for these RPMs to eventually live in the xen-c6 repo. I was
 wondering what are the steps for making this happen, and also if it
 would be possible to make this happen before the dojo next Friday (12
 July).

 My RPMS are in a bit of an experimental state, and I'd really appreciate
 people's feedback. It might be too soon to merge them into xen-c6 by next
 week, but it would be nice if I could point people at an online copy
 somewhere. Perhaps we could make a xen-c6-experimental repo or something? I
 could then rsync new builds regularly and put setup instructions on the
 CentOS wiki.

 Cheers,
 Dave



 We can provide a public Yum repository with these SRPMS and RPMS, if
 that would help. Thanks,

 Mike
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Gordon Messmer]

On 07/08/2012 08:47 AM, Pasi Kärkkäinen wrote:
 There are other Xen-based virtualization solutions out there aswell with full 
 support.

That's true, but I'm guessing that a lot of people on this list are here 
specifically because they're not paying for support.

Whether that's true or not, if you're deploying virtualization *on 
CentOS*, KVM is really the only rational choice.  Xen hosting support is 
no longer a part of new releases.


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Re: [CentOS] XEN or KVM - performance/stability/security?

[Pasi Kärkkäinen]

On Tue, Jun 05, 2012 at 01:50:30PM -0700, Gordon Messmer wrote:
 On 06/04/2012 11:36 PM, Pasi Kärkkäinen wrote:
 
  Xen PV has been rock solid for me :)
 
 Maybe, if we ignore the fact that you seem to be familiar with the 
 problem of xenconsoled failing and preventing guests from booting.
 

The el5 xenconsoled bug:

1) Affected only 32bit (i686) hosts running el5 Xen
2) It was fixed years ago on upstream Xen
3) It is already fixed in rhel5/centos5
4) It didn't affect 64bit (x86_64) hosts running el5 Xen
5) It was easy to workaround by killing+restarting xenconsoled


  Xen is supported by Red Hat support in RHEL5.
 
 Yes, and RHEL5 will be supported for several years.  However, there does 
 not appear to be a plan to support Xen in the future, after RHEL5 
 expires.  It would be irrational to invest time and money into training 
 on Xen with no expectation that those skills will remain valuable in the 
 future.
 

There are other Xen-based virtualization solutions out there aswell with full 
support.

-- Pasi

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Pasi Kärkkäinen]

On Sat, May 12, 2012 at 02:38:34PM -0400, Steve Thompson wrote:
 On Sun, 6 May 2012, Pasi Kärkkäinen wrote:
 
 with fork performance I assume you're comparing Xen PV to KVM ?
 Yes, PV has disadvantage (per design) for that workload, since the hypervisor
 needs to check and verify each new process page table, and that has some 
 performance hit.
 For good fork performance you can use Xen HVM VMs, which will perform well 
 for that workload,
 and won't have the mentioned performance hit.
 
 I used both PV and HVM VMs. I don't have the details to hand at the
 moment, but KVM was superior to both. PV drivers where applicable. I
 have been running KVM for about 15 months now, with 30 VM's on one
 host and 38 VM's on another. It has been solid; no problems, but
 unfortunately I had
 problems with Xen.
 

And Xen has been rock solid on my production systems.
So it depends :)

-- Pasi

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Pasi Kärkkäinen]

On Fri, May 11, 2012 at 03:46:43PM -0700, Gordon Messmer wrote:
 A late reply, but hopefully a useful set of feedback for the archives:
 
 On 04/20/2012 05:59 AM, Rafa?? Radecki wrote:
  Key factors from my opint of view are:
  - stability (which one runs more smoothly on CentOS?)
 
 I found that xenconsoled could frequently crash in Xen dom0, and that 
 guests would be unable to reboot until it was fixed.  I also found that 
 paravirt CentOS domUs would not boot if they were updated before the 
 dom0.


This was a problem in RHEL5/CentOS5 Xen. It was fixed in upstream Xen years ago.
I think it was fixed finally in RHEL5/CentOS5 Xen in 5.7 or 5.8.

The workaround was to simply kill+restart xenconsoled. No reboot required.
Also I think the xenconsoled bug only happened on 32bit hosts.

  In short, Xen paravirt was very fragile and troublesome.  I never 
 tested Xen with hardware virtualization.
 

Xen PV has been rock solid for me :)

 I have had no such problems with KVM.  In my experience KVM is much more 
 stable than Xen paravirtualization.  Xen HVM probably would suffer at 
 least some of the same problems.
 

You should compare Xen HVM with KVM, and you said you haven't been running Xen 
HVM.

 
 There have been bugs that allow guests to escalate privileges and access 
 host resources, but they're relatively few.  I don't think there's a 
 significant difference between the two in this area.
 
 Overall I advise the use of KVM.  It should be more stable, and has the 
 advantage of Red Hat support.
 

Xen is supported by Red Hat support in RHEL5.

-- Pasi

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Gordon Messmer]

On 06/04/2012 11:36 PM, Pasi Kärkkäinen wrote:

 Xen PV has been rock solid for me :)

Maybe, if we ignore the fact that you seem to be familiar with the 
problem of xenconsoled failing and preventing guests from booting.

 Xen is supported by Red Hat support in RHEL5.

Yes, and RHEL5 will be supported for several years.  However, there does 
not appear to be a plan to support Xen in the future, after RHEL5 
expires.  It would be irrational to invest time and money into training 
on Xen with no expectation that those skills will remain valuable in the 
future.

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Gordon Messmer]

On 05/16/2012 02:47 PM, Luke S. Crawford wrote:
 (how are the paravirt drivers in KVM these days?  I have a server
 full of kvm guests running some ancient version of ubuntu I will be
 moving to RHEL6 shortly.)

Since RHEL guests have the virtio block drivers built-in, I never get 
around to benchmarking them against non-virtio block devices.
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Luke S. Crawford]

On Fri, May 11, 2012 at 03:46:43PM -0700, Gordon Messmer wrote:
 A late reply, but hopefully a useful set of feedback for the archives:
 
 On 04/20/2012 05:59 AM, Rafał Radecki wrote:
  Key factors from my opint of view are:
  - stability (which one runs more smoothly on CentOS?)
 
 I found that xenconsoled could frequently crash in Xen dom0, and that 
 guests would be unable to reboot until it was fixed.  I also found that 
 paravirt CentOS domUs would not boot if they were updated before the 
 dom0.  In short, Xen paravirt was very fragile and troublesome.  I never 
 tested Xen with hardware virtualization.

This particular problem was fixed some time ago, it hasn't happened
to my (many) dom0s in more than a year.

The RHEL5 Xen dom0 was garbage until 5.3 or so.  To the point where I'd
compile my own and deal with the pain of using a non-rhel kernel with
a rehl userland.

Stability has improved vastly.

  - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
  without pv drivers))
 
 PV drivers will make some difference, but the biggest performance 
 difference you'll see is probably the difference between file-backed VMs 
 and LVM-backed VMs.  File-backed VMs are extremely slow.  Whichever 
 system you choose, use LVMs as the backing for your guests.

My experience has been that using qemu for disk has something of a 
multiplier effect;  e.g. it makes slow spinning disk noticably 
slower.  The paravirtualized drivers help immensely in that regard.

(how are the paravirt drivers in KVM these days?  I have a server 
full of kvm guests running some ancient version of ubuntu I will be
moving to RHEL6 shortly.)  
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Theo Band]

On 05/12/2012 12:46 AM, Gordon Messmer wrote:
 A late reply, but hopefully a useful set of feedback for the archives:
Well let me share my experience as well.
 On 04/20/2012 05:59 AM, Rafał Radecki wrote:
 Key factors from my opint of view are:
 - stability (which one runs more smoothly on CentOS?)
 I found that xenconsoled could frequently crash in Xen dom0, and that 
 guests would be unable to reboot until it was fixed.  I also found that 
 paravirt CentOS domUs would not boot if they were updated before the 
 dom0.  In short, Xen paravirt was very fragile and troublesome.  I never 
 tested Xen with hardware virtualization.

 I have had no such problems with KVM.  In my experience KVM is much more 
 stable than Xen paravirtualization.  Xen HVM probably would suffer at 
 least some of the same problems.
I have some machine that were very unstable under load (max uptime some
weeks, then a crash). They were running CentOS5 with XEN kernel. First I
thought it was hardware related, but once a non-Xen kernel was loaded
and I migrated the VMs to KVM the machines are rock solid.
I must say I still have two machines running Xen and they have no
problem the last year. So it's probably also related to the specified
hardware configuration.

Theo

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Steve Thompson]

On Sun, 6 May 2012, Pasi Kärkkäinen wrote:


with fork performance I assume you're comparing Xen PV to KVM ?
Yes, PV has disadvantage (per design) for that workload, since the hypervisor
needs to check and verify each new process page table, and that has some 
performance hit.
For good fork performance you can use Xen HVM VMs, which will perform well 
for that workload,
and won't have the mentioned performance hit.


I used both PV and HVM VMs. I don't have the details to hand at the 
moment, but KVM was superior to both. PV drivers where applicable. I have 
been running KVM for about 15 months now, with 30 VM's on one host and 38 
VM's on another. It has been solid; no problems, but unfortunately I had

problems with Xen.

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Dennis Jacobfeuerborn]

On 05/12/2012 12:46 AM, Gordon Messmer wrote:
 A late reply, but hopefully a useful set of feedback for the archives:
 
 On 04/20/2012 05:59 AM, Rafał Radecki wrote:
 Key factors from my opint of view are:
 - stability (which one runs more smoothly on CentOS?)
 
 I found that xenconsoled could frequently crash in Xen dom0, and that 
 guests would be unable to reboot until it was fixed.  I also found that 
 paravirt CentOS domUs would not boot if they were updated before the 
 dom0.  In short, Xen paravirt was very fragile and troublesome.  I never 
 tested Xen with hardware virtualization.
 
 I have had no such problems with KVM.  In my experience KVM is much more 
 stable than Xen paravirtualization.  Xen HVM probably would suffer at 
 least some of the same problems.
 
 - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
 without pv drivers))
 
 PV drivers will make some difference, but the biggest performance 
 difference you'll see is probably the difference between file-backed VMs 
 and LVM-backed VMs.  File-backed VMs are extremely slow.  Whichever 
 system you choose, use LVMs as the backing for your guests.
 
 - security
 
 There have been bugs that allow guests to escalate privileges and access 
 host resources, but they're relatively few.  I don't think there's a 
 significant difference between the two in this area.

sVirt mitigates this danger somewhat on the host side so even if you run
into such an issue it is very hard to utilize such an export.

Regards,
  Dennis
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Gordon Messmer]

A late reply, but hopefully a useful set of feedback for the archives:

On 04/20/2012 05:59 AM, Rafał Radecki wrote:
 Key factors from my opint of view are:
 - stability (which one runs more smoothly on CentOS?)

I found that xenconsoled could frequently crash in Xen dom0, and that 
guests would be unable to reboot until it was fixed.  I also found that 
paravirt CentOS domUs would not boot if they were updated before the 
dom0.  In short, Xen paravirt was very fragile and troublesome.  I never 
tested Xen with hardware virtualization.

I have had no such problems with KVM.  In my experience KVM is much more 
stable than Xen paravirtualization.  Xen HVM probably would suffer at 
least some of the same problems.

 - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
 without pv drivers))

PV drivers will make some difference, but the biggest performance 
difference you'll see is probably the difference between file-backed VMs 
and LVM-backed VMs.  File-backed VMs are extremely slow.  Whichever 
system you choose, use LVMs as the backing for your guests.

 - security

There have been bugs that allow guests to escalate privileges and access 
host resources, but they're relatively few.  I don't think there's a 
significant difference between the two in this area.

Overall I advise the use of KVM.  It should be more stable, and has the 
advantage of Red Hat support.

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Pasi Kärkkäinen]

On Mon, Apr 23, 2012 at 01:02:03PM -0400, Steve Thompson wrote:
 On Mon, 23 Apr 2012, Peter Peltonen wrote:
 
  I've been quite happy with Xen under CentOS5. For CentOS6 the
  situation is a bit more problematic, as RH switched to KVM and left
  Xen behind.
 
 I used Xen for about four or five years before switching to KVM. I like 
 KVM better in every way, and for my fork-heavy workloads, the performance 
 is a lot better than Xen. It is also much easier to use and is in my 
 experience more stable.
 

with fork performance I assume you're comparing Xen PV to KVM ? 

Yes, PV has disadvantage (per design) for that workload, since the hypervisor
needs to check and verify each new process page table, and that has some 
performance hit.

For good fork performance you can use Xen HVM VMs, which will perform well 
for that workload,
and won't have the mentioned performance hit.

And of course with Xen HVM VMs you should use the Xen PVHVM drivers so the 
disk/net 
IO paths are optimized and bypassing all the emulation.

CentOS5 and CentOS6 do have Xen PVHVM drivers.

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Pasi Kärkkäinen]

On Mon, Apr 23, 2012 at 11:01:12PM +0300, Peter Peltonen wrote:
 Hi,
 
 On Mon, Apr 23, 2012 at 10:54 PM, aurfalien aurfal...@gmail.com wrote:
 
  I also prefer KVM over Xen, mainly I don;t have to do anything special when 
  maintaining the env.
 
  But I haven't notice an improvement over Xen.
 
  I really like the fact that the guest OS has a stock kernel, etc..
 
 I do not quite see how Xen requires one to do something special for
 maintenance? With pygrub you can use the stock kernel with your Xen
 domUs just fine. I have not seen any issues with stability either, but
 then again I am running mostly just web and mail servers without
 really high traffic.
 
 But if KVM would offer improvements for performance over Xen, I should
 perhaps try it out, as sometimes when doing backups and other things
 that require a lot of disk I/O a better performance could be wished
 for...
 

Disk performance is usually mainly limited by the number of physical disk 
spindles,
and the raid level, and not so much about virtualization.

Anyway some Xen PV vs. Xen PVHVM vs. KVM benchmarks from XenSummit 2011:
http://xen.org/files/xensummit_santaclara11/aug3/6_StefanoS_PVHVM.pdf

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Karanbir Singh]

On 04/24/2012 10:58 AM, Mihamina Rakotomandimby wrote:
 LXC sounds interesting: are there any yum repositries / RPMs /
 tutorials for CentOS available?
 
 You dont need rpms: the libvirt directly use the LXC API.
 A tutorial: http://goo.gl/kQOxm
 

there are some limitations with libvirt/lxc at the moment - eg. needing
to build the root images outside of libvirt.

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Mihamina Rakotomandimby]

On 04/23/2012 06:44 PM, Peter Peltonen wrote:
 I would add some LXC pins for quick ehanced chroot, depending on the use
 case
 LXC sounds interesting: are there any yum repositries / RPMs /
 tutorials for CentOS available?

You dont need rpms: the libvirt directly use the LXC API.
A tutorial: http://goo.gl/kQOxm

All you need is to
- setup the XML
- define a VM from it
- start the VM

No more, for the basic example.
Really fun.
Of course, when you need a custom environment, you'll need to read 
further: but it's still fun :-)


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Re: [CentOS] XEN or KVM - performance/stability/security?

[Dennis Jacobfeuerborn]

On 04/24/2012 11:58 AM, Mihamina Rakotomandimby wrote:
 On 04/23/2012 06:44 PM, Peter Peltonen wrote:
 I would add some LXC pins for quick ehanced chroot, depending on the use
 case
 LXC sounds interesting: are there any yum repositries / RPMs /
 tutorials for CentOS available?
 
 You dont need rpms: the libvirt directly use the LXC API.
 A tutorial: http://goo.gl/kQOxm
 
 All you need is to
 - setup the XML
 - define a VM from it
 - start the VM
 
 No more, for the basic example.
 Really fun.
 Of course, when you need a custom environment, you'll need to read 
 further: but it's still fun :-)

Remember that currently LXC isn't very secure (as mentioned in the tutorial
link) so you probably don't want to use it for important stuff in a
production environment.


Regards,
  Dennis
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Mihamina Rakotomandimby]

On 04/20/2012 04:23 PM, Dmitry Cherkasov wrote:
 On CentOS6 all is fine
 with KVM right out of the box.

 Never used XEN so cannot compare.

Same here.
I would add some LXC pins for quick ehanced chroot, depending on the use 
case.

I think the OP should provide more details: What is benchmarked 
(Network? HD?...)


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Re: [CentOS] XEN or KVM - performance/stability/security?

[Peter Peltonen]

Hi,

On Mon, Apr 23, 2012 at 6:29 PM, Mihamina Rakotomandimby
miham...@rktmb.org wrote:
 I would add some LXC pins for quick ehanced chroot, depending on the use
 case.

LXC sounds interesting: are there any yum repositries / RPMs /
tutorials for CentOS available?


I've been quite happy with Xen under CentOS5. For CentOS6 the
situation is a bit more problematic, as RH switched to KVM and left
Xen behind.

Best,
Peter
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Steve Thompson]

On Mon, 23 Apr 2012, Peter Peltonen wrote:

 I've been quite happy with Xen under CentOS5. For CentOS6 the
 situation is a bit more problematic, as RH switched to KVM and left
 Xen behind.

I used Xen for about four or five years before switching to KVM. I like 
KVM better in every way, and for my fork-heavy workloads, the performance 
is a lot better than Xen. It is also much easier to use and is in my 
experience more stable.

Steve

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Re: [CentOS] XEN or KVM - performance/stability/security?

[aurfalien]

On Apr 23, 2012, at 1:02 PM, Steve Thompson wrote:

 On Mon, 23 Apr 2012, Peter Peltonen wrote:
 
 I've been quite happy with Xen under CentOS5. For CentOS6 the
 situation is a bit more problematic, as RH switched to KVM and left
 Xen behind.
 
 I used Xen for about four or five years before switching to KVM. I like 
 KVM better in every way, and for my fork-heavy workloads, the performance 
 is a lot better than Xen. It is also much easier to use and is in my 
 experience more stable.
 
 Steve

I also prefer KVM over Xen, mainly I don;t have to do anything special when 
maintaining the env.

But I haven't notice an improvement over Xen.

I really like the fact that the guest OS has a stock kernel, etc..

- aurf
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Peter Peltonen]

Hi,

On Mon, Apr 23, 2012 at 10:54 PM, aurfalien aurfal...@gmail.com wrote:

 I also prefer KVM over Xen, mainly I don;t have to do anything special when 
 maintaining the env.

 But I haven't notice an improvement over Xen.

 I really like the fact that the guest OS has a stock kernel, etc..

I do not quite see how Xen requires one to do something special for
maintenance? With pygrub you can use the stock kernel with your Xen
domUs just fine. I have not seen any issues with stability either, but
then again I am running mostly just web and mail servers without
really high traffic.

But if KVM would offer improvements for performance over Xen, I should
perhaps try it out, as sometimes when doing backups and other things
that require a lot of disk I/O a better performance could be wished
for...

Regards,
Peter
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Re: [CentOS] XEN or KVM - performance/stability/security?

[aurfalien]

On Apr 23, 2012, at 4:01 PM, Peter Peltonen wrote:

 Hi,
 
 On Mon, Apr 23, 2012 at 10:54 PM, aurfalien aurfal...@gmail.com wrote:
 
 I also prefer KVM over Xen, mainly I don;t have to do anything special when 
 maintaining the env.
 
 But I haven't notice an improvement over Xen.
 
 I really like the fact that the guest OS has a stock kernel, etc..
 
 I do not quite see how Xen requires one to do something special for
 maintenance?

Regarding Centos 6 there are some extra things to install.

Even when I deviated from the included version of Xen in 5, I had to pay 
special attention.

As for stock kernels, you mean HVMs right?

I was speaking more about PVMs which is faster and more flexible then HVMs.

I never had any issues with Xen other then VGA and USB pass through.

But Xen ran well for me.

As for convenience, I'm into KVM now, very cool features with pass throughs, 
graphics etc...

- aurf
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Re: [CentOS] XEN or KVM - performance/stability/security?

[aurfalien]

On Apr 23, 2012, at 4:01 PM, Peter Peltonen wrote:

 Hi,
 
 On Mon, Apr 23, 2012 at 10:54 PM, aurfalien aurfal...@gmail.com wrote:
 
 I also prefer KVM over Xen, mainly I don;t have to do anything special when 
 maintaining the env.
 
 But I haven't notice an improvement over Xen.
 
 I really like the fact that the guest OS has a stock kernel, etc..
 
 I do not quite see how Xen requires one to do something special for
 maintenance? With pygrub you can use the stock kernel with your Xen
 domUs just fine. I have not seen any issues with stability either, but
 then again I am running mostly just web and mail servers without
 really high traffic.
 
 But if KVM would offer improvements for performance over Xen, I should
 perhaps try it out, as sometimes when doing backups and other things
 that require a lot of disk I/O a better performance could be wished
 for...

Forgot to add there there are some cool options for increasing disk IO.

Load up KVM and check it out.  I'm pretty happy with it.

- aurf
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Peter Peltonen]

On Mon, Apr 23, 2012 at 11:11 PM, aurfalien aurfal...@gmail.com wrote:
 As for stock kernels, you mean HVMs right?

 I was speaking more about PVMs which is faster and more flexible then HVMs.

No, with pygrub you can run a stock kernel on a PVM domU:
http://wiki.xensource.com/xenwiki/PyGrub


 I never had any issues with Xen other then VGA and USB pass through.

 But Xen ran well for me.

 As for convenience, I'm into KVM now, very cool features with pass throughs, 
 graphics etc...

USB pass through has worked fine for me under Xen. Never had the need
for graphics for my servers. For desktops I've been happy with
Parallels and VirtualBox.

But from comments it sounds like KVM is maturing and I should perhaps
give it a try.


Regards,
Peter
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Dennis Jacobfeuerborn]

On 04/23/2012 10:11 PM, aurfalien wrote:
 On Apr 23, 2012, at 4:01 PM, Peter Peltonen wrote:
 
 Hi,

 On Mon, Apr 23, 2012 at 10:54 PM, aurfalien aurfal...@gmail.com wrote:

 I also prefer KVM over Xen, mainly I don;t have to do anything special when 
 maintaining the env.

 But I haven't notice an improvement over Xen.

 I really like the fact that the guest OS has a stock kernel, etc..

 I do not quite see how Xen requires one to do something special for
 maintenance?
 
 Regarding Centos 6 there are some extra things to install.
 
 Even when I deviated from the included version of Xen in 5, I had to pay 
 special attention.
 
 As for stock kernels, you mean HVMs right?
 
 I was speaking more about PVMs which is faster and more flexible then HVMs.
 

The PVM/HVM distinction isn't really that relevant any more on modern
hardware and modern hypervisors since most of the overhead is eliminated
with hardware features (Nested Page Tables, etc.) and special guest drivers.

Regards,
  Dennis
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Re: [CentOS] XEN or KVM - performance/stability/security?

[John R Pierce]

On 04/23/12 5:12 PM, Dennis Jacobfeuerborn wrote:
 The PVM/HVM distinction isn't really that relevant any more on modern
 hardware and modern hypervisors since most of the overhead is eliminated
 with hardware features (Nested Page Tables, etc.) and special guest drivers.

special guest drivers is pretty much what paravirtualization is about.



-- 
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Dennis Jacobfeuerborn]

On 04/24/2012 03:08 AM, John R Pierce wrote:
 On 04/23/12 5:12 PM, Dennis Jacobfeuerborn wrote:
 The PVM/HVM distinction isn't really that relevant any more on modern
 hardware and modern hypervisors since most of the overhead is eliminated
 with hardware features (Nested Page Tables, etc.) and special guest drivers.
 
 special guest drivers is pretty much what paravirtualization is about.

Exactly, but only since CPU got hardware extensions for virtualization.
Before that the CPU could also be paravirtualized and that made a
significant difference in performance.

With that advantage gone though the old distinction between a PVM guest
and HVM guest doesn't really matter that much any more (virt-manager asks
you which of the two you want to install for example). Now you only have a
guest that may or may not run certain paravirtualized drivers.

Regards,
  Dennis
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[CentOS] XEN or KVM - performance/stability/security?

[Rafał Radecki]

Hi all.

I am currently building a small test cloud based on Eucalyptus 2.0.3 and
CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN.
KVM is the default in CentOS 6 but I have read also many good things (for
example PV guest machines, isolation between Dom0 and DomU) about XEN.

Key factors from my opint of view are:
- stability (which one runs more smoothly on CentOS?)
- performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
without pv drivers))
- security

Could you share your experience in these areas?

Best regards,
Rafal Radecki.
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Karanbir Singh]

On 04/20/2012 01:59 PM, Rafał Radecki wrote:
 I am currently building a small test cloud base..
...
 Could you share your experience in these areas?

try the centos-virt list ? Lots of people there ( including people who
write a lot of the code behind some of these things! )

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Re: [CentOS] XEN or KVM - performance/stability/security?

[Jonathan Vomacka]

On 4/20/2012 8:59 AM, Rafał Radecki wrote:
 Hi all.

 I am currently building a small test cloud based on Eucalyptus 2.0.3 and
 CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN.
 KVM is the default in CentOS 6 but I have read also many good things (for
 example PV guest machines, isolation between Dom0 and DomU) about XEN.

 Key factors from my opint of view are:
 - stability (which one runs more smoothly on CentOS?)
 - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
 without pv drivers))
 - security

 Could you share your experience in these areas?

 Best regards,
 Rafal Radecki.
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Xen all the way. That's just my opinion though.
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Rafał Radecki]

Why?

2012/4/20 Jonathan Vomacka juvi...@gmail.com

 On 4/20/2012 8:59 AM, Rafał Radecki wrote:
  Hi all.
 
  I am currently building a small test cloud based on Eucalyptus 2.0.3 and
  CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN.
  KVM is the default in CentOS 6 but I have read also many good things (for
  example PV guest machines, isolation between Dom0 and DomU) about XEN.
 
  Key factors from my opint of view are:
  - stability (which one runs more smoothly on CentOS?)
  - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
  without pv drivers))
  - security
 
  Could you share your experience in these areas?
 
  Best regards,
  Rafal Radecki.
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Re: [CentOS] XEN or KVM - performance/stability/security?

[Dmitry Cherkasov]

Hi,

KVM if used as it is will show very poor performance on CentOS5. To
achieve better results you need to update kernel to at least 2.6.32
and compile newer versions of libvirt and qemu. On CentOS6 all is fine
with KVM right out of the box.

Never used XEN so cannot compare.


Dmitry Cherkasov



2012/4/20 Rafał Radecki radecki.ra...@gmail.com:
 Hi all.

 I am currently building a small test cloud based on Eucalyptus 2.0.3 and
 CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN.
 KVM is the default in CentOS 6 but I have read also many good things (for
 example PV guest machines, isolation between Dom0 and DomU) about XEN.

 Key factors from my opint of view are:
 - stability (which one runs more smoothly on CentOS?)
 - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
 without pv drivers))
 - security

 Could you share your experience in these areas?

 Best regards,
 Rafal Radecki.
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Re: [CentOS] Xen Install manager won't let me install anything.

[Pasi Kärkkäinen]

On Thu, May 05, 2011 at 04:53:22PM -0400, Martes G Wigglesworth wrote:
 
 On 05/05/2011 09:09 AM, Pasi Kärkkäinen wrote:
  It sounds like your hardware does not have HVM support,
  which means you can only run PV VMs.
 Thanks for the reply.
 
 You are correct.
 
 I have two P4 32-bit machines that I just picked up and wanted to use 
 them for testing until I can afford to upgrade to the 12-core 
 MB/Processors that I bought these 2u chassis into which I plan to install.
 
 I have never used xen, and it just seems kind of odd that you cannot 
 simply install from the hard drive, like on virtualbox.  Anyhow, I could 
 only figure that was the outlying factor.
 
 I could not locate that aspect of the virt-manager docs, so I will check 
 again.
 

Not being able to install from ISO image as PV VM is a virt-manager limitation.
(and partly centos/rhel distro limitation).


 Anyhow, now I am fighting with SL-Linux's installation media for i386, 
 having the ability to be seen, and booted, but inside their own boot 
 menue, it forces you to re-verify that you have install media. (Even 
 though it is running from the media in the first place.  Then Xen 
 magically can't see the iso that SL linux is running from.)
 
 Are there any good (I guess dated, now that everything is mulit-core) 
 docs on how to work with paravirtualization, since I have to deal with 
 this weird network install setup?  It seems that I can put in the 
 explicit path to the local-disk-installed ISO image, but the second it 
 boots, nothing can be found, and it asks me to put in a url, etc...
 

RHEL/CentOS docs have examples...
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization/index.html

cmdline virt-install example to install PV RHEL5/CentOS5:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization/chap-Virtualization-Guest_operating_system_installation_procedures.html#sect-Virtualization-Installing_Red_Hat_Enterprise_Linux_5_as_a_para_virtualized_guest

Fedora can be installed as Xen PV VM in the same way..
just give fedora mirror URL instead of RHEL/CentOS mirror URL.


 
 I know this sounds incoherent, but I am burnt out from exams.
  Installation for PV (paravirtualized) VMs is only supported
  by using netinstall in virt-manager.
 
  HVM (fully virtualized) VMs can be installed from ISO image.
 Thanks for the input, and would appreciate any further direction on 
 reading further on real-world installs, not the docs where they assume 
 you have a quad 12-core processor super server so everything thing just 
 works in virtualmode... )  I guess this is more for virt-manager, but I 
 think you will understand what I mean if you check the doc site for virt 
 manager.  They don't even mention that there is a limitation such as 
 what you have described, except to say there is a limitation.
 
 Sorry for the ramble. Need more RedBull, or maybe not so much Lol..
 

Hehe.

You can also use other tools than virt-manager/virt-install to install VMs.

- debootstrap to install Debian/Ubuntu VMs.
- thirdparty xen-tools to install Debian/Ubuntu VMs.
- febootstrap to install fedora.
- various chroot tricks to install rpm-based distros.
- Fedora native installer, by downloading the fedora installer pxeboot
  kernel + initrd and booting them as xen pv domU.
- Debian/Ubuntu native installer, by downloading the debian 6.0 or ubuntu 10.04
  installer netinstall kernel + initrd and booting them as xen pv domU.


See the end of the tutorial for an example how to install ubuntu manually using 
the distro installer:
http://wiki.xen.org/xenwiki/Fedora13Xen4Tutorial

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Re: [CentOS] Xen Install manager won't let me install anything.

[Pasi Kärkkäinen]

On Thu, May 05, 2011 at 12:45:41AM -0400, Martes G Wigglesworth wrote:
 
 Greetings all.
 
 I am attempting to install dom-u guests on a vanilla install of Centos 
 5.6.  I am attempting to use the Xen Manager and it 1) won't let me 
 choose ANYTHING but network install, which is quite odd to say the 
 least, and 2) won't let my freebsd install iso complete.  I am a novice 
 with Xen, however, it doesn't make sense even in the most minimally 
 supported system that it would default to a more complex install method 
 such as network, or PXE why does the Centos install of Xen Manager 
 installation wizard force you to only choose network install?
 

It sounds like your hardware does not have HVM support,
which means you can only run PV VMs.

Installation for PV (paravirtualized) VMs is only supported 
by using netinstall in virt-manager.

HVM (fully virtualized) VMs can be installed from ISO image.

-- Pasi

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Re: [CentOS] Xen Install manager won't let me install anything.

[Martes G Wigglesworth]

On 05/05/2011 09:09 AM, Pasi Kärkkäinen wrote:
 It sounds like your hardware does not have HVM support,
 which means you can only run PV VMs.
Thanks for the reply.

You are correct.

I have two P4 32-bit machines that I just picked up and wanted to use 
them for testing until I can afford to upgrade to the 12-core 
MB/Processors that I bought these 2u chassis into which I plan to install.

I have never used xen, and it just seems kind of odd that you cannot 
simply install from the hard drive, like on virtualbox.  Anyhow, I could 
only figure that was the outlying factor.

I could not locate that aspect of the virt-manager docs, so I will check 
again.

Anyhow, now I am fighting with SL-Linux's installation media for i386, 
having the ability to be seen, and booted, but inside their own boot 
menue, it forces you to re-verify that you have install media. (Even 
though it is running from the media in the first place.  Then Xen 
magically can't see the iso that SL linux is running from.)

Are there any good (I guess dated, now that everything is mulit-core) 
docs on how to work with paravirtualization, since I have to deal with 
this weird network install setup?  It seems that I can put in the 
explicit path to the local-disk-installed ISO image, but the second it 
boots, nothing can be found, and it asks me to put in a url, etc...


I know this sounds incoherent, but I am burnt out from exams.
 Installation for PV (paravirtualized) VMs is only supported
 by using netinstall in virt-manager.

 HVM (fully virtualized) VMs can be installed from ISO image.
Thanks for the input, and would appreciate any further direction on 
reading further on real-world installs, not the docs where they assume 
you have a quad 12-core processor super server so everything thing just 
works in virtualmode... )  I guess this is more for virt-manager, but I 
think you will understand what I mean if you check the doc site for virt 
manager.  They don't even mention that there is a limitation such as 
what you have described, except to say there is a limitation.

Sorry for the ramble. Need more RedBull, or maybe not so much Lol..

-- 
Respectfully,


Martes G Wigglesworth
M. G. Wigglesworth Holdings, LLC
www.mgwigglesworth.net

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[CentOS] Xen Install manager won't let me install anything.

[Martes G Wigglesworth]

Greetings all.

I am attempting to install dom-u guests on a vanilla install of Centos 
5.6.  I am attempting to use the Xen Manager and it 1) won't let me 
choose ANYTHING but network install, which is quite odd to say the 
least, and 2) won't let my freebsd install iso complete.  I am a novice 
with Xen, however, it doesn't make sense even in the most minimally 
supported system that it would default to a more complex install method 
such as network, or PXE why does the Centos install of Xen Manager 
installation wizard force you to only choose network install?

-- 
Respectfully,


Martes G Wigglesworth
M. G. Wigglesworth Holdings, LLC
www.mgwigglesworth.net

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[CentOS] Xen stack scheme

[Jussi Hirvi]

I need to restructure my server farm from tower PC:s to a minimal amount 
of 1U rack servers. I am going to rely on xen virtualization, as KVM 
seems not to be very mature yet.

My current problem is the mail server, which uses a lot of CPU and I/O. 
A dedicated machine would be the best option. But would there be any 
sense in this:

- run the mail server in xen dom0 (to get full native performance)
- append a couple of light-weight servers as domU:s (like name server)

- Jussi Hirvi

-- 
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Topeliuksenkatu 15 C * 00250 Helsinki * Finland
Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms)
jussi.hi...@greenspot.fi * http://www.greenspot.fi
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Re: [CentOS] Xen stack scheme

[Simon Matter]

 I need to restructure my server farm from tower PC:s to a minimal amount
 of 1U rack servers. I am going to rely on xen virtualization, as KVM
 seems not to be very mature yet.

 My current problem is the mail server, which uses a lot of CPU and I/O.
 A dedicated machine would be the best option. But would there be any
 sense in this:

 - run the mail server in xen dom0 (to get full native performance)
 - append a couple of light-weight servers as domU:s (like name server)

I don't know if it's recommended that way but at least it works fine.

Simon

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Re: [CentOS] Xen stack scheme

[Jussi Hirvi]

On 4.3.2011 10.52, Simon Matter wrote:
 I don't know if it's recommended that way but at least it works fine.

Hm, that is kind of the only important thing. :-)

If it is not recommended, there have to be better reasons for that than 
mere tidiness.

- Jussi
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Re: [CentOS] Xen stack scheme

[Pasi Kärkkäinen]

On Fri, Mar 04, 2011 at 11:11:52AM +0200, Jussi Hirvi wrote:
 On 4.3.2011 10.52, Simon Matter wrote:
  I don't know if it's recommended that way but at least it works fine.
 
 Hm, that is kind of the only important thing. :-)
 
 If it is not recommended, there have to be better reasons for that than 
 mere tidiness.
 

Dom0 should be reserved only for management toolstack and minimal amount
of services (storage/network backends).

Actually dom0 is a *VM* aswell (see xm list), although it has more direct
access to the hardware and thus to storage. 

You're probably limited by the disk IOPS anyway, so it shouldn't
matter that much if you run the service in dom0 or in domU,
so go for domU, since that's the more safe bet.

-- Pasi

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Re: [CentOS] Xen stack scheme

[Pasi Kärkkäinen]

On Fri, Mar 04, 2011 at 11:37:08AM +0200, Pasi Kärkkäinen wrote:
 On Fri, Mar 04, 2011 at 11:11:52AM +0200, Jussi Hirvi wrote:
  On 4.3.2011 10.52, Simon Matter wrote:
   I don't know if it's recommended that way but at least it works fine.
  
  Hm, that is kind of the only important thing. :-)
  
  If it is not recommended, there have to be better reasons for that than 
  mere tidiness.
  
 
 Dom0 should be reserved only for management toolstack and minimal amount
 of services (storage/network backends).
 
 Actually dom0 is a *VM* aswell (see xm list), although it has more direct
 access to the hardware and thus to storage. 
 
 You're probably limited by the disk IOPS anyway, so it shouldn't
 matter that much if you run the service in dom0 or in domU,
 so go for domU, since that's the more safe bet.
 

Oh, you should also limit and dedicate fixed amount of memory
for dom0, say, 768 MB, or whatever you need there.

http://wiki.xensource.com/xenwiki/XenBestPractices

-- Pasi

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Re: [CentOS] Xen stack scheme

[Paul Heinlein]

On Fri, 4 Mar 2011, Jussi Hirvi wrote:

 I need to restructure my server farm from tower PC:s to a minimal 
 amount of 1U rack servers. I am going to rely on xen virtualization, 
 as KVM seems not to be very mature yet.

What part of KVM seems immature to you? I deploy public-facing 
machines using both it and Xen, and I can't really speak to any 
difference in performance or small-scall management.

-- 
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Re: [CentOS] Xen stack scheme

[compdoc]

What part of KVM seems immature to you? I deploy public-facing
machines using both it and Xen, and I can't really speak to any
difference in performance or small-scall management.

I like kvm - no issues


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Re: [CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

On Wed, Feb 23, 2011 at 4:33 PM, Ross Walker rswwal...@gmail.com wrote:
 On Feb 23, 2011, at 3:42 AM, Rudi Ahlers r...@softdux.com wrote:

 On Wed, Feb 23, 2011 at 9:06 AM, yonatan pingle
 yonatan.pin...@gmail.com wrote:
 you should have a look at your I/O disk status.

 try with iostat -dx 5 to see the disk utilization info over time.
 when it comes to slowdown on a virtual environment on a Desktop grade
 machine,  i suspect disk I/O latency and bottleneck as a cause.

 Thanx, I don't know how to interpret the results (yet), but here's the
 current output:

 Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
 avgqu-sz   await  svctm  %util

 Knowing the columns helps here,

 rrqm/s and wrqm/s, mean read/write requests merged a second, shows how well 
 scheduler is merging contiguous io operations

 r/s and w/s, read/write io operations a second

 rsec/s and wsec/s, read/write sectors a second, I usually use the -k option 
 so it displays as kilobytes a second

 avgrq-sz, shows average request size in the unit of choice, here being 
 sectors, I wish it'd separate reads from writes, but oh well

 avgqu-sz, average amount of io operations waiting for service, smaller is 
 better

 await, average time an io operation waited on queue to be serviced in ms, 
 again smaller is better

 svctm, last time it took to service an io operation, how long the drive took 
 to perform the operation from when it left queue to when a result was returned

 %util, the estimated drive utilization based on svctm, await and avgqu-sz

 For lockups though I'd look at dmesg and xen log, xmlog I think is the 
 command.

 The number one reason for lockups though is most likely memory contention 
 between domUs and dom0.

 What are you running in dom0? What are your memory reservations like?

 -Ross
 ___


I see a lot of these errors in /var/log/messages shortly before it crashed:



Feb 22 15:27:14 zaxen01 kernel: HighMem: empty
Feb 22 15:27:14 zaxen01 kernel: 918 pagecache pages
Feb 22 15:27:14 zaxen01 kernel: Swap cache: add 2248198, delete
2248009, find 160685591/160898897, race 0+453
Feb 22 15:27:14 zaxen01 kernel: Free swap  = 0kB
Feb 22 15:27:14 zaxen01 kernel: Total swap = 4194296kB
Feb 22 15:27:14 zaxen01 kernel: Free swap:0kB
Feb 22 15:27:14 zaxen01 kernel: 133120 pages of RAM
Feb 22 15:27:14 zaxen01 kernel: 22818 reserved pages
Feb 22 15:27:16 zaxen01 kernel: 105840 pages shared
Feb 22 15:27:16 zaxen01 kernel: 189 pages swap cached
Feb 22 15:27:17 zaxen01 kernel: Out of memory: Killed process 17464,
UID 99, (sendmail).
Feb 23 00:35:38 zaxen01 syslogd 1.4.1: restart.
Feb 23 00:35:38 zaxen01 kernel: klogd 1.4.1, log source = /proc/kmsg started.
Feb 23 00:35:38 zaxen01 kernel: Bootdata ok (command line is ro
root=/dev/System/root rhgb quiet xencons=tty6)
Feb 23 00:35:38 zaxen01 kernel: Linux version 2.6.18-194.32.1.el5xen
(mockbu...@builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat
4.1.2-48)) #1 SMP
Wed Jan 5 18:44:24 EST 2011
Feb 23 00:35:38 zaxen01 kernel: BIOS-provided physical RAM map:
Feb 23 00:35:38 zaxen01 kernel:  Xen:  -
2080 (usable)
Feb 23 00:35:38 zaxen01 kernel: DMI 2.4 present.
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x01]
lapic_id[0x00] enabled)
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x03]
lapic_id[0x02] enabled)
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x02]
lapic_id[0x01] enabled)
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x04]
lapic_id[0x03] enabled)
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC_NMI (acpi_id[0x01] dfl dfl
lint[0x1])
Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC_NMI (acpi_id[0x02] dfl dfl
lint[0x1])
Feb 23 00:35:38 zaxen01 kernel: ACPI: IOAPIC (id[0x02]
address[0xfec0] gsi_base[0])
Feb 23 00:35:38 zaxen01 kernel: IOAPIC[0]: apic_id 2, version 32,
address 0xfec0, GSI 0-23
Feb 23 00:35:38 zaxen01 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 0
global_irq 2 dfl dfl)
Feb 23 00:35:38 zaxen01 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 9
global_irq 9 high level)
Feb 23 00:35:38 zaxen01 kernel: Setting APIC routing to xen
Feb 23 00:35:38 zaxen01 kernel: Using ACPI (MADT) for SMP
configuration information
Feb 23 00:35:38 zaxen01 kernel: Allocating PCI resources starting at
d400 (gap: d000:2ff0)
Feb 23 00:35:38 zaxen01 kernel: Built 1 zonelists.  Total pages: 133120
Feb 23 00:35:38 zaxen01 kernel: Kernel command line: ro
root=/dev/System/root rhgb quiet xencons=tty6
Feb 23 00:35:38 zaxen01 kernel: Initializing CPU#0
Feb 23 00:35:38 zaxen01 kernel: PID hash table entries: 4096 (order:
12, 32768 bytes)






@Ross,

dom0 is a XEN host for CloudMin,so it runs Apache + Webmin, MySQL  Exim

-- 
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
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Cell: 082 554 7532
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Ross Walker]

On Feb 25, 2011, at 4:29 AM, Rudi Ahlers r...@softdux.com wrote:

 On Wed, Feb 23, 2011 at 4:33 PM, Ross Walker rswwal...@gmail.com wrote:
 On Feb 23, 2011, at 3:42 AM, Rudi Ahlers r...@softdux.com wrote:
 
 On Wed, Feb 23, 2011 at 9:06 AM, yonatan pingle
 yonatan.pin...@gmail.com wrote:
 you should have a look at your I/O disk status.
 
 try with iostat -dx 5 to see the disk utilization info over time.
 when it comes to slowdown on a virtual environment on a Desktop grade
 machine,  i suspect disk I/O latency and bottleneck as a cause.
 
 Thanx, I don't know how to interpret the results (yet), but here's the
 current output:
 
 Device: rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
 avgqu-sz   await  svctm  %util
 
 Knowing the columns helps here,
 
 rrqm/s and wrqm/s, mean read/write requests merged a second, shows how well 
 scheduler is merging contiguous io operations
 
 r/s and w/s, read/write io operations a second
 
 rsec/s and wsec/s, read/write sectors a second, I usually use the -k option 
 so it displays as kilobytes a second
 
 avgrq-sz, shows average request size in the unit of choice, here being 
 sectors, I wish it'd separate reads from writes, but oh well
 
 avgqu-sz, average amount of io operations waiting for service, smaller is 
 better
 
 await, average time an io operation waited on queue to be serviced in ms, 
 again smaller is better
 
 svctm, last time it took to service an io operation, how long the drive took 
 to perform the operation from when it left queue to when a result was 
 returned
 
 %util, the estimated drive utilization based on svctm, await and avgqu-sz
 
 For lockups though I'd look at dmesg and xen log, xmlog I think is the 
 command.
 
 The number one reason for lockups though is most likely memory contention 
 between domUs and dom0.
 
 What are you running in dom0? What are your memory reservations like?
 
 
 I see a lot of these errors in /var/log/messages shortly before it crashed:
 
 
 
 Feb 22 15:27:14 zaxen01 kernel: HighMem: empty
 Feb 22 15:27:14 zaxen01 kernel: 918 pagecache pages
 Feb 22 15:27:14 zaxen01 kernel: Swap cache: add 2248198, delete
 2248009, find 160685591/160898897, race 0+453
 Feb 22 15:27:14 zaxen01 kernel: Free swap  = 0kB
 Feb 22 15:27:14 zaxen01 kernel: Total swap = 4194296kB
 Feb 22 15:27:14 zaxen01 kernel: Free swap:0kB
 Feb 22 15:27:14 zaxen01 kernel: 133120 pages of RAM
 Feb 22 15:27:14 zaxen01 kernel: 22818 reserved pages
 Feb 22 15:27:16 zaxen01 kernel: 105840 pages shared
 Feb 22 15:27:16 zaxen01 kernel: 189 pages swap cached
 Feb 22 15:27:17 zaxen01 kernel: Out of memory: Killed process 17464,
 UID 99, (sendmail).
 Feb 23 00:35:38 zaxen01 syslogd 1.4.1: restart.
 Feb 23 00:35:38 zaxen01 kernel: klogd 1.4.1, log source = /proc/kmsg started.
 Feb 23 00:35:38 zaxen01 kernel: Bootdata ok (command line is ro
 root=/dev/System/root rhgb quiet xencons=tty6)
 Feb 23 00:35:38 zaxen01 kernel: Linux version 2.6.18-194.32.1.el5xen
 (mockbu...@builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat
 4.1.2-48)) #1 SMP
 Wed Jan 5 18:44:24 EST 2011
 Feb 23 00:35:38 zaxen01 kernel: BIOS-provided physical RAM map:
 Feb 23 00:35:38 zaxen01 kernel:  Xen:  -
 2080 (usable)
 Feb 23 00:35:38 zaxen01 kernel: DMI 2.4 present.
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x01]
 lapic_id[0x00] enabled)
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x03]
 lapic_id[0x02] enabled)
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x02]
 lapic_id[0x01] enabled)
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC (acpi_id[0x04]
 lapic_id[0x03] enabled)
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC_NMI (acpi_id[0x01] dfl dfl
 lint[0x1])
 Feb 23 00:35:38 zaxen01 kernel: ACPI: LAPIC_NMI (acpi_id[0x02] dfl dfl
 lint[0x1])
 Feb 23 00:35:38 zaxen01 kernel: ACPI: IOAPIC (id[0x02]
 address[0xfec0] gsi_base[0])
 Feb 23 00:35:38 zaxen01 kernel: IOAPIC[0]: apic_id 2, version 32,
 address 0xfec0, GSI 0-23
 Feb 23 00:35:38 zaxen01 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 0
 global_irq 2 dfl dfl)
 Feb 23 00:35:38 zaxen01 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 9
 global_irq 9 high level)
 Feb 23 00:35:38 zaxen01 kernel: Setting APIC routing to xen
 Feb 23 00:35:38 zaxen01 kernel: Using ACPI (MADT) for SMP
 configuration information
 Feb 23 00:35:38 zaxen01 kernel: Allocating PCI resources starting at
 d400 (gap: d000:2ff0)
 Feb 23 00:35:38 zaxen01 kernel: Built 1 zonelists.  Total pages: 133120
 Feb 23 00:35:38 zaxen01 kernel: Kernel command line: ro
 root=/dev/System/root rhgb quiet xencons=tty6
 Feb 23 00:35:38 zaxen01 kernel: Initializing CPU#0
 Feb 23 00:35:38 zaxen01 kernel: PID hash table entries: 4096 (order:
 12, 32768 bytes)

It seems dom0's memory got under pressure from the other domUs.

Make sure to set an absolute minimum of memory for dom0 in xend.conf or using 
the boot option (forgot what it is). I always made it to the OS min of 256MB, 
but if you are doing more 

Re: [CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

On Fri, Feb 25, 2011 at 4:21 PM, Ross Walker rswwal...@gmail.com wrote:



 It seems dom0's memory got under pressure from the other domUs.

 Make sure to set an absolute minimum of memory for dom0 in xend.conf or using 
 the boot option (forgot what it is). I always made it to the OS min of 256MB, 
 but if you are doing more in dom0 you'd want more.

 On a side, I might run all management apps in a VM and manage dom0 from that 
 domU.


 -Ross

 ___


I already set dom0 to 512MB, but it seems it might not be enough. I
was hoping I could optimize it a bit more though

-- 
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Ross Walker]

On Feb 25, 2011, at 9:28 AM, Rudi Ahlers r...@softdux.com wrote:

 On Fri, Feb 25, 2011 at 4:21 PM, Ross Walker rswwal...@gmail.com wrote:
 
 
 
 It seems dom0's memory got under pressure from the other domUs.
 
 Make sure to set an absolute minimum of memory for dom0 in xend.conf or 
 using the boot option (forgot what it is). I always made it to the OS min of 
 256MB, but if you are doing more in dom0 you'd want more.
 
 On a side, I might run all management apps in a VM and manage dom0 from that 
 domU.
 
 
 -Ross
 
 ___
 
 
 I already set dom0 to 512MB, but it seems it might not be enough. I
 was hoping I could optimize it a bit more though

Try setting the max as well, then it's memory allocation is fixed, say 512/512. 
Then the only memory pressure is between apps in dom0.

-Ross

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Re: [CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

On Wed, Feb 23, 2011 at 9:06 AM, yonatan pingle
yonatan.pin...@gmail.com wrote:
 you should have a look at your I/O disk status.

 try with iostat -dx 5 to see the disk utilization info over time.
 when it comes to slowdown on a virtual environment on a Desktop grade
 machine,  i suspect disk I/O latency and bottleneck as a cause.

Thanx, I don't know how to interpret the results (yet), but here's the
current output:


Device: rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda   0.0027.20  0.00  6.80 0.00   448.0065.88
0.000.59   0.35   0.24
sda1  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
sda2  0.0027.20  0.00  6.80 0.00   448.0065.88
0.000.59   0.35   0.24
dm-0  0.00 0.00  0.00 27.80 0.00   222.40 8.00
0.010.35   0.09   0.24
dm-1  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-2  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-3  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-4  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-5  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-6  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-7  0.00 0.00  0.00  0.40 0.00 6.4016.00
0.000.00   0.00   0.00
dm-8  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-9  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-10 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-11 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-12 0.00 0.00  0.00  2.80 0.0097.6034.86
0.000.00   0.00   0.00
dm-13 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-14 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-15 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-16 0.00 0.00  0.00  3.00 0.00   121.6040.53
0.000.00   0.00   0.00
dm-17 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00

Although, most of those values change the whole time, as such:

Device: rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda   0.00 1.00  0.00  0.80 0.0017.6022.00
0.000.00   0.00   0.00
sda1  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
sda2  0.00 1.00  0.00  0.80 0.0017.6022.00
0.000.00   0.00   0.00
dm-0  0.00 0.00  0.00  1.40 0.0011.20 8.00
0.000.00   0.00   0.00
dm-1  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-2  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-3  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-4  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-5  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-6  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-7  0.00 0.00  0.00  0.40 0.00 6.4016.00
0.000.00   0.00   0.00
dm-8  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-9  0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-10 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-11 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-12 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-13 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-14 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-15 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-16 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00
dm-17 0.00 0.00  0.00  0.00 0.00 0.00 0.00
0.000.00   0.00   0.00





 check that your 

Re: [CentOS] how to optimize CentOS XEN dom0?

[Ross Walker]

On Feb 23, 2011, at 3:42 AM, Rudi Ahlers r...@softdux.com wrote:

 On Wed, Feb 23, 2011 at 9:06 AM, yonatan pingle
 yonatan.pin...@gmail.com wrote:
 you should have a look at your I/O disk status.
 
 try with iostat -dx 5 to see the disk utilization info over time.
 when it comes to slowdown on a virtual environment on a Desktop grade
 machine,  i suspect disk I/O latency and bottleneck as a cause.
 
 Thanx, I don't know how to interpret the results (yet), but here's the
 current output:
 
 Device: rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
 avgqu-sz   await  svctm  %util

Knowing the columns helps here,

rrqm/s and wrqm/s, mean read/write requests merged a second, shows how well 
scheduler is merging contiguous io operations

r/s and w/s, read/write io operations a second

rsec/s and wsec/s, read/write sectors a second, I usually use the -k option so 
it displays as kilobytes a second

avgrq-sz, shows average request size in the unit of choice, here being sectors, 
I wish it'd separate reads from writes, but oh well

avgqu-sz, average amount of io operations waiting for service, smaller is better

await, average time an io operation waited on queue to be serviced in ms, again 
smaller is better

svctm, last time it took to service an io operation, how long the drive took to 
perform the operation from when it left queue to when a result was returned

%util, the estimated drive utilization based on svctm, await and avgqu-sz

For lockups though I'd look at dmesg and xen log, xmlog I think is the command.

The number one reason for lockups though is most likely memory contention 
between domUs and dom0.

What are you running in dom0? What are your memory reservations like?

-Ross
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[CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

Hi,

I have a problematic CentOS XEN server and hope someone could point me
in the right direction to optimize it a bit.

The server runs on a Core2Quad 9300, with 8GB RAM (max motherboard can
take, 1U chassis) on an Intel motherboard with a 1TB SATA HDD.

dom0 is set to 512MB limit with a few small XEM VM's running:


root@zaxen01:[~]$ xm list
Name  ID Mem(MiB) VCPUs State   Time(s)
Domain-0   0  512 4 r- 96.5
actionco.vm3 1519 1 -b 14.8
byracers.vm4  511 1 -b 85.7
ns15  511 1 -b 22.3
picturestravel6  255 1 -b 13.3
rafttheworld   7  255 1 -b 11.3
zafepres.vm8  511 1 -b 19.0




the server itself seems to eat up a lot of resources:


root@zaxen01:[~]$ free -m
 total   used   free sharedbuffers cached
Mem:   512472 39  0 13215
-/+ buffers/cache:244268
Swap: 4095  0   4095[/CODE]


Yet, it only has XEN, Webmin (since it's a CloudMin XEN server), Exim,
Apache and a few other services running:



root@zaxen01:[~]$ chkconfig --list |grep 3:on |awk '{print $1}' |sort
acpid
auditd
crond
csf
dhcpd
exim
haldaemon
httpd
iptables
iscsi
iscsid
kudzu
lfd
lvm2-monitor
mdmonitor
network
qemu
restorecond
setroubleshoot
smartd
snmpd
sshd
syslog
sysstat
webmin
xend
xendomains




Is there anything I can optimize on such a server?



The server runs CentOS 5.5 x64:

root@zaxen01:[~]$ cat /etc/redhat-release
CentOS release 5.5 (Final)

root@zaxen01:[~]$ uname -a
Linux zaxen01.softdux.com 2.6.18-194.32.1.el5xen #1 SMP Wed Jan 5
18:44:24 EST 2011 x86_64 x86_64 x86_64 GNU/Linux

with  Xen version 3.1.2-194.32.1.el5


And there's the xm dmesg output:


Xen version 3.1.2-194.32.1.el5 (mockbu...@centos.org) (gcc version
4.1.2 20080704 (Red Hat 4.1.2-48)) Wed Jan  5 17:43:03 EST 2011
 Latest ChangeSet: unavailable

(XEN) Command line: dom0_mem=512M
(XEN) Video information:
(XEN)  VGA is text mode 80x25, font 8x16
(XEN)  VBE/DDC methods: V2; EDID transfer time: 1 seconds
(XEN) Disc information:
(XEN)  Found 1 MBR signatures
(XEN)  Found 1 EDD information structures
(XEN) Xen-e820 RAM map:
(XEN)   - 0008f000 (usable)
(XEN)  0008f000 - 000a (reserved)
(XEN)  000e - 0010 (reserved)
(XEN)  0010 - cf53f000 (usable)
(XEN)  cf53f000 - cf54b000 (reserved)
(XEN)  cf54b000 - cf62 (usable)
(XEN)  cf62 - cf6e8000 (ACPI NVS)
(XEN)  cf6e8000 - cf6ec000 (usable)
(XEN)  cf6ec000 - cf6f1000 (ACPI data)
(XEN)  cf6f1000 - cf6f2000 (usable)
(XEN)  cf6f2000 - cf6ff000 (ACPI data)
(XEN)  cf6ff000 - cf70 (usable)
(XEN)  cf70 - d000 (reserved)
(XEN)  fff0 - 0001 (reserved)
(XEN)  0001 - 00023000 (usable)
(XEN) System RAM: 8181MB (8378020kB)
(XEN) Xen heap: 13MB (13720kB)
(XEN) Domain heap initialised: DMA width 32 bits
(XEN) Processor #0 7:7 APIC version 20
(XEN) Processor #2 7:7 APIC version 20
(XEN) Processor #1 7:7 APIC version 20
(XEN) Processor #3 7:7 APIC version 20
(XEN) IOAPIC[0]: apic_id 2, version 32, address 0xfec0, GSI 0-23
(XEN) Enabling APIC mode:  Flat.  Using 1 I/O APICs
(XEN) Using scheduler: SMP Credit Scheduler (credit)
(XEN) Detected 2485.797 MHz processor.
(XEN) HVM: VMX enabled
(XEN) VMX: MSR intercept bitmap enabled
(XEN) I/O virtualisation disabled
(XEN) CPU0: Intel(R) Core(TM)2 Quad  CPU   Q9300  @ 2.50GHz stepping 07
(XEN) Booting processor 1/2 eip 9
(XEN) CPU1: Intel(R) Core(TM)2 Quad  CPU   Q9300  @ 2.50GHz stepping 07
(XEN) Booting processor 2/1 eip 9
(XEN) CPU2: Intel(R) Core(TM)2 Quad  CPU   Q9300  @ 2.50GHz stepping 07
(XEN) Booting processor 3/3 eip 9
(XEN) CPU3: Intel(R) Core(TM)2 Quad  CPU   Q9300  @ 2.50GHz stepping 07
(XEN) Total of 4 processors activated.
(XEN) ENABLING IO-APIC IRQs
(XEN)  - Using new ACK method
(XEN) Platform timer overflows in 2 jiffies.
(XEN) Platform timer is 1.193MHz PIT
(XEN) Brought up 4 CPUs
(XEN) *** LOADING DOMAIN 0 ***
(XEN) elf_parse_binary: phdr: paddr=0x8020 memsz=0x2f4d70
(XEN) elf_parse_binary: phdr: paddr=0x804f4d80 memsz=0x14c510
(XEN) elf_parse_binary: phdr: paddr=0x80642000 memsz=0xc08
(XEN) elf_parse_binary: phdr: paddr=0x80644000 memsz=0x11be8c
(XEN) elf_parse_binary: memory: 0x8020 - 0x8075fe8c
(XEN) elf_xen_parse_note: GUEST_OS = linux
(XEN) elf_xen_parse_note: GUEST_VERSION = 2.6
(XEN) elf_xen_parse_note: XEN_VERSION = xen-3.0
(XEN

Re: [CentOS] how to optimize CentOS XEN dom0?

[Kenni Lund]

2011/2/23 Rudi Ahlers r...@softdux.com:
 Hi,

 I have a problematic CentOS XEN server and hope someone could point me
 in the right direction to optimize it a bit.

(SNIP)

 the server itself seems to eat up a lot of resources:


 root@zaxen01:[~]$ free -m
             total       used       free     shared    buffers     cached
 Mem:           512        472         39          0         13        215
 -/+ buffers/cache:        244        268
 Swap:         4095          0       4095[/CODE]

244MB RAM in use and 0MB swap...looks good to me.

 Is there anything I can optimize on such a server?

It's hard to give any advices without further information about what
the problem is.

Best regards
Kenni
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Cameron Kerr]

On 23/02/11 12:29, Rudi Ahlers wrote:
 Hi,
 
 I have a problematic CentOS XEN server and hope someone could point me
 in the right direction to optimize it a bit.
 
 The server runs on a Core2Quad 9300, with 8GB RAM (max motherboard can
 take, 1U chassis) on an Intel motherboard with a 1TB SATA HDD.
 
 dom0 is set to 512MB limit with a few small XEM VM's running:
 
 
 root@zaxen01:[~]$ xm list
 Name  ID Mem(MiB) VCPUs State   Time(s)
 Domain-0   0  512 4 r- 96.5

dom0 is responsible for IO, so you would normally expect it have it
spend more time in the CPU. You could try pinning it to its own CPU...

 actionco.vm3 1519 1 -b 14.8
 byracers.vm4  511 1 -b 85.7
 ns15  511 1 -b 22.3
 picturestravel6  255 1 -b 13.3
 rafttheworld   7  255 1 -b 11.3
 zafepres.vm8  511 1 -b 19.0
 
 
 
 
 the server itself seems to eat up a lot of resources:
 
 
 root@zaxen01:[~]$ free -m
  total   used   free sharedbuffers cached
 Mem:   512472 39  0 13215
 -/+ buffers/cache:244268
 Swap: 4095  0   4095[/CODE]

This looks normal. Remember, Linux uses a memory full model, so
although it appears that there is 39MB of real memory available, there
is actually 268, with most of that being used to cache filesystem data.

If you want to see how loaded a system is, with respect to memory
pressure, try using 'vmstat' and look for how often it is swapping pages
into and out of swap.

Also, have a look at the Xen users guide. It has some
performance-enhancing tips that you should be aware of. In particular,
realise that dom0 is a little special, particularly with regard to IO.

 Is there anything I can optimize on such a server?

Not entirely sure what you need to optimise at this point. So far I see
a reasonably normal-looking system (although, to be frank, I don't have
a lot of experience with Xen at present).

Hope it helps,
Cameron
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

On Wed, Feb 23, 2011 at 1:37 AM, Kenni Lund ke...@kelu.dk wrote:
 2011/2/23 Rudi Ahlers r...@softdux.com:
 Hi,

 I have a problematic CentOS XEN server and hope someone could point me
 in the right direction to optimize it a bit.

 (SNIP)

 the server itself seems to eat up a lot of resources:


 root@zaxen01:[~]$ free -m
             total       used       free     shared    buffers     cached
 Mem:           512        472         39          0         13        215
 -/+ buffers/cache:        244        268
 Swap:         4095          0       4095[/CODE]

 244MB RAM in use and 0MB swap...looks good to me.

Well, I just send a tech over to reset the server since it was locked
up. He couldn't login to the console, or SSH and had to reset the
server.


 Is there anything I can optimize on such a server?

 It's hard to give any advices without further information about what
 the problem is.


Fair enough, what other info can I give you?


-- 
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Ian Murray]

Are they paravirt of HVM guests? qemu might have something to do with it if HVM 
guests are involved.




- Original Message 
 From: Rudi Ahlers r...@softdux.com
 To: CentOS mailing list centos@centos.org
 Sent: Tue, 22 February, 2011 23:29:29
 Subject: [CentOS] how to optimize CentOS XEN dom0?
 
 Hi,
 
 I have a problematic CentOS XEN server and hope someone could point  me
 in the right direction to optimize it a bit.
 
 The server runs on a  Core2Quad 9300, with 8GB RAM (max motherboard can
 take, 1U chassis) on an  Intel motherboard with a 1TB SATA HDD.
 
 dom0 is set to 512MB limit with a  few small XEM VM's running:
 
 
 root@zaxen01:[~]$ xm list
 NameID Mem(MiB) VCPUs StateTime(s)
 Domain-00   512 4 r- 96.5
 actionco.vm  3 1519 1 -b  14.8
 byracers.vm 4   511 1 -b 85.7
 ns1  5  511 1  -b 22.3
 picturestravel 6   255 1 -b 13.3
 rafttheworld 7  255 1 -b  11.3
 zafepres.vm 8   511 1 -b 19.0
 
 
 
 
 the  server itself seems to eat up a lot of resources:
 
 
 root@zaxen01:[~]$  free -m
  totalused   free sharedbuffers  cached
 Mem:   512 472 39   0 13215
 -/+  buffers/cache:244 268
 Swap: 4095   0   4095[/CODE]
 
 
 Yet, it only has XEN, Webmin  (since it's a CloudMin XEN server), Exim,
 Apache and a few other services  running:
 
 
 
 root@zaxen01:[~]$ chkconfig --list |grep 3:on |awk  '{print $1}'  |sort
 acpid
 auditd
 crond
 csf
 dhcpd
 exim
 haldaemon
 httpd
 iptables
 iscsi
 iscsid
 kudzu
 lfd
 lvm2-monitor
 mdmonitor
 network
 qemu
 restorecond
 setroubleshoot
 smartd
 snmpd
 sshd
 syslog
 sysstat
 webmin
 xend
 xendomains
 
 
 
 
 Is  there anything I can optimize on such a server?
 
 
 
 The server runs  CentOS 5.5 x64:
 
 root@zaxen01:[~]$ cat /etc/redhat-release
 CentOS  release 5.5 (Final)
 
 root@zaxen01:[~]$ uname -a
 Linux  zaxen01.softdux.com 2.6.18-194.32.1.el5xen #1 SMP Wed Jan 5
 18:44:24 EST 2011  x86_64 x86_64 x86_64 GNU/Linux
 
 with  Xen version  3.1.2-194.32.1.el5
 
 
 And there's the xm dmesg output:
 
 
 Xen  version 3.1.2-194.32.1.el5 (mockbu...@centos.org) (gcc  version
 4.1.2 20080704 (Red Hat 4.1.2-48)) Wed Jan  5 17:43:03 EST  2011
  Latest ChangeSet: unavailable
 
 (XEN) Command line:  dom0_mem=512M
 (XEN) Video information:
 (XEN)  VGA is text mode 80x25,  font 8x16
 (XEN)  VBE/DDC methods: V2; EDID transfer time: 1  seconds
 (XEN) Disc information:
 (XEN)  Found 1 MBR  signatures
 (XEN)  Found 1 EDD information structures
 (XEN) Xen-e820  RAM map:
 (XEN)   - 0008f000  (usable)
 (XEN)  0008f000 - 000a  (reserved)
 (XEN)  000e - 0010  (reserved)
 (XEN)  0010 - cf53f000  (usable)
 (XEN)  cf53f000 - cf54b000  (reserved)
 (XEN)  cf54b000 - cf62  (usable)
 (XEN)  cf62 - cf6e8000 (ACPI  NVS)
 (XEN)  cf6e8000 - cf6ec000 (usable)
 (XEN)   cf6ec000 - cf6f1000 (ACPI data)
 (XEN)  cf6f1000  - cf6f2000 (usable)
 (XEN)  cf6f2000 - cf6ff000  (ACPI data)
 (XEN)  cf6ff000 - cf70  (usable)
 (XEN)  cf70 - d000  (reserved)
 (XEN)  fff0 - 0001  (reserved)
 (XEN)  0001 - 00023000 (usable)
 (XEN)  System RAM: 8181MB (8378020kB)
 (XEN) Xen heap: 13MB (13720kB)
 (XEN) Domain  heap initialised: DMA width 32 bits
 (XEN) Processor #0 7:7 APIC version  20
 (XEN) Processor #2 7:7 APIC version 20
 (XEN) Processor #1 7:7 APIC  version 20
 (XEN) Processor #3 7:7 APIC version 20
 (XEN) IOAPIC[0]: apic_id  2, version 32, address 0xfec0, GSI 0-23
 (XEN) Enabling APIC mode:   Flat.  Using 1 I/O APICs
 (XEN) Using scheduler: SMP Credit Scheduler  (credit)
 (XEN) Detected 2485.797 MHz processor.
 (XEN) HVM: VMX  enabled
 (XEN) VMX: MSR intercept bitmap enabled
 (XEN) I/O virtualisation  disabled
 (XEN) CPU0: Intel(R) Core(TM)2 Quad  CPU   Q9300  @  2.50GHz stepping 07
 (XEN) Booting processor 1/2 eip 9
 (XEN) CPU1:  Intel(R) Core(TM)2 Quad  CPU   Q9300  @ 2.50GHz stepping  07
 (XEN) Booting processor 2/1 eip 9
 (XEN) CPU2: Intel(R) Core(TM)2  Quad  CPU   Q9300  @ 2.50GHz stepping 07
 (XEN) Booting  processor 3/3 eip 9
 (XEN) CPU3: Intel(R) Core(TM)2 Quad  CPUQ9300  @ 2.50GHz stepping 07
 (XEN) Total of 4 processors  activated.
 (XEN) ENABLING IO-APIC IRQs
 (XEN)  - Using new ACK  method
 (XEN) Platform timer overflows in 2 jiffies.
 (XEN) Platform timer  is 1.193MHz PIT
 (XEN) Brought up 4

Re: [CentOS] how to optimize CentOS XEN dom0?

[Rudi Ahlers]

On Wed, Feb 23, 2011 at 1:41 AM, Ian Murray murra...@yahoo.co.uk wrote:
 Are they paravirt of HVM guests? qemu might have something to do with it if 
 HVM
 guests are involved.



Uhm, I know that I should know this, but how do I tell from a quick
glance? It's almost 2am in the morning here, and I'm a bit too tired
to think straight right now. I've been reading up on a lot of forums
and other google search results before I posted here.

The VM's were originally created with HyperVM, but then imported into CloudMin.



-- 
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
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Re: [CentOS] how to optimize CentOS XEN dom0?

[yonatan pingle]

you should have a look at your I/O disk status.

try with iostat -dx 5 to see the disk utilization info over time.
when it comes to slowdown on a virtual environment on a Desktop grade
machine,  i suspect disk I/O latency and bottleneck as a cause.

check that your disk is running at its optimal state.
look at some indicators , such the the I/O utilization averages,
server load averages
hddtemp /dev/sda will check for heating ( under high load it might )

in any case , you still got plenty of ram to spend.


On Wed, Feb 23, 2011 at 1:46 AM, Rudi Ahlers r...@softdux.com wrote:
 On Wed, Feb 23, 2011 at 1:41 AM, Ian Murray murra...@yahoo.co.uk wrote:
 Are they paravirt of HVM guests? qemu might have something to do with it if 
 HVM
 guests are involved.



 Uhm, I know that I should know this, but how do I tell from a quick
 glance? It's almost 2am in the morning here, and I'm a bit too tired
 to think straight right now. I've been reading up on a lot of forums
 and other google search results before I posted here.

 The VM's were originally created with HyperVM, but then imported into 
 CloudMin.



 --
 Kind Regards
 Rudi Ahlers
 SoftDux

 Website: http://www.SoftDux.com
 Technical Blog: http://Blog.SoftDux.com
 Office: 087 805 9573
 Cell: 082 554 7532
 ___
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-- 
Best Regards,
Yonatan Pingle
RHCT | RHCSA | CCNA1
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Re: [CentOS] how to optimize CentOS XEN dom0?

[Geoff Galitz]

 The server runs on a Core2Quad 9300, with 8GB RAM (max motherboard can
 take, 1U chassis) on an Intel motherboard with a 1TB SATA HDD.

 dom0 is set to 512MB limit with a few small XEM VM's running:


 root@zaxen01:[~]$ xm list
 Name  ID Mem(MiB) VCPUs State 
 Time(s)
 Domain-0   0  512 4 r-  
 96.5
 actionco.vm3 1519 1 -b  
 14.8
 byracers.vm4  511 1 -b  
 85.7
 ns15  511 1 -b  
 22.3
 picturestravel6  255 1 -b 13.3
 rafttheworld   7  255 1 -b  
 11.3
 zafepres.vm8  511 1 -b  
 19.0


...

What are the actual symptoms you are seeing?

In general I found that tuning the disk scheduler and also the Xen guest 
scheduler to be helpful:

http://wiki.xensource.com/xenwiki/CreditScheduler
http://www.cyberciti.biz/faq/linux-change-io-scheduler-for-harddisk/

Also, I always recommend building Xen servers to use SAS drives rather than 
SATA because SATA are half duplex while SAS is full duplex, meaning under 
higher or more random IO you will better throughput.   In my experience  I 
see almost double the performance when using SAS over SATA, but our 
environments are IO heavy and may not reflect the realities of your 
environment.

I would also suggest, running disk IO stats in the VMs simultaneously while 
running iostat or vmstat in Dom0 to get a good read for where bottlenecks 
really are.  I actually prefer to use the simple postmark utility as it is 
relatively simple and avoids disk caching issues which skew your results.



 

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Re: [CentOS] Xen; xm usb-add syntax - or - where is xm usb-attach

[Pasi Kärkkäinen]

On Thu, Jan 20, 2011 at 10:53:15AM -0800, aurfal...@gmail.com wrote:
 On Jan 18, 2011, at 5:40 AM, Pasi Kärkkäinen wrote:
 
  On Mon, Jan 17, 2011 at 04:46:49PM -0800, aurfal...@gmail.com wrote:
  Hi all,
 
  I'm running Centos 5.5 with Xen 4.0.1
 
  Would like to use a USB key (not a block device) in my domU.
 
  Dom0 lsusb yields;
 
  Bus 002 Device 004: ID 064f:0bd8 ABC-Systems AB CDE/FG
 
  xm usb-add shows;
 
  Usage: xm usb-add domain [host:bus.addr]  
  [host:vendor_id:product_id]
 
  Not sure what combo will work in this case.
 
  However, I've read some notes regarding xm usb-attach.  What subset  
  of
  Xen do I need for this command to show?
 
 
  http://wiki.xensource.com/xenwiki/XenUSBPassthrough
 
 
 Hi Pasi,
 
 This wasn't very helpful.
 
 Is there any definitive answer on wether USB passthrough works using  
 Xen 4.0.1 and Centos 5.5?
 

centos5 kernel-xen does NOT have xen pvusb drivers included,
so pvusb won't work, unless you grab/build the drivers from 
http://xenbits.xen.org/linux-2.6.18-xen.hg

Xen HVM guest qemu-dm USB passthru (usb 1.1) should be available,
but that is only for Xen HVM VMs, not for PV domUs.

If using pvops 2.6.32 dom0 kernel, then pvusb drivers
are available here: 
http://lists.xensource.com/archives/html/xen-devel/2011-01/msg00354.html

-- Pasi

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Re: [CentOS] Xen; xm usb-add syntax - or - where is xm usb-attach

[Pasi Kärkkäinen]

On Sat, Jan 22, 2011 at 04:20:28PM +0200, Pasi Kärkkäinen wrote:
 On Thu, Jan 20, 2011 at 10:53:15AM -0800, aurfal...@gmail.com wrote:
  On Jan 18, 2011, at 5:40 AM, Pasi Kärkkäinen wrote:
  
   On Mon, Jan 17, 2011 at 04:46:49PM -0800, aurfal...@gmail.com wrote:
   Hi all,
  
   I'm running Centos 5.5 with Xen 4.0.1
  
   Would like to use a USB key (not a block device) in my domU.
  
   Dom0 lsusb yields;
  
   Bus 002 Device 004: ID 064f:0bd8 ABC-Systems AB CDE/FG
  
   xm usb-add shows;
  
   Usage: xm usb-add domain [host:bus.addr]  
   [host:vendor_id:product_id]
  
   Not sure what combo will work in this case.
  
   However, I've read some notes regarding xm usb-attach.  What subset  
   of
   Xen do I need for this command to show?
  
  
   http://wiki.xensource.com/xenwiki/XenUSBPassthrough
  
  
  Hi Pasi,
  
  This wasn't very helpful.
  
  Is there any definitive answer on wether USB passthrough works using  
  Xen 4.0.1 and Centos 5.5?
  
 
 centos5 kernel-xen does NOT have xen pvusb drivers included,
 so pvusb won't work, unless you grab/build the drivers from 
 http://xenbits.xen.org/linux-2.6.18-xen.hg
 
 Xen HVM guest qemu-dm USB passthru (usb 1.1) should be available,
 but that is only for Xen HVM VMs, not for PV domUs.
 
 If using pvops 2.6.32 dom0 kernel, then pvusb drivers
 are available here: 
 http://lists.xensource.com/archives/html/xen-devel/2011-01/msg00354.html
 

One option is to use Xen PCI passthru to pass the USB controller
(pci device) to the domU.

-- Pasi

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Re: [CentOS] Xen; xm usb-add syntax - or - where is xm usb-attach

[aurfalien]

On Jan 18, 2011, at 5:40 AM, Pasi Kärkkäinen wrote:

 On Mon, Jan 17, 2011 at 04:46:49PM -0800, aurfal...@gmail.com wrote:
 Hi all,

 I'm running Centos 5.5 with Xen 4.0.1

 Would like to use a USB key (not a block device) in my domU.

 Dom0 lsusb yields;

 Bus 002 Device 004: ID 064f:0bd8 ABC-Systems AB CDE/FG

 xm usb-add shows;

 Usage: xm usb-add domain [host:bus.addr]  
 [host:vendor_id:product_id]

 Not sure what combo will work in this case.

 However, I've read some notes regarding xm usb-attach.  What subset  
 of
 Xen do I need for this command to show?


 http://wiki.xensource.com/xenwiki/XenUSBPassthrough


Hi Pasi,

This wasn't very helpful.

Is there any definitive answer on wether USB passthrough works using  
Xen 4.0.1 and Centos 5.5?

Seems like it fails miserably based on the posts I have read.

KVM on the other hand seems to work.

- aurf


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Re: [CentOS] Xen; xm usb-add syntax - or - where is xm usb-attach

[Pasi Kärkkäinen]

On Mon, Jan 17, 2011 at 04:46:49PM -0800, aurfal...@gmail.com wrote:
 Hi all,
 
 I'm running Centos 5.5 with Xen 4.0.1
 
 Would like to use a USB key (not a block device) in my domU.
 
 Dom0 lsusb yields;
 
 Bus 002 Device 004: ID 064f:0bd8 ABC-Systems AB CDE/FG
 
 xm usb-add shows;
 
 Usage: xm usb-add domain [host:bus.addr] [host:vendor_id:product_id]
 
 Not sure what combo will work in this case.
 
 However, I've read some notes regarding xm usb-attach.  What subset of  
 Xen do I need for this command to show?
 

http://wiki.xensource.com/xenwiki/XenUSBPassthrough

Hopefully that helps.

-- Pasi

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[CentOS] Xen; xm usb-add syntax - or - where is xm usb-attach

[aurfalien]

Hi all,

I'm running Centos 5.5 with Xen 4.0.1

Would like to use a USB key (not a block device) in my domU.

Dom0 lsusb yields;

Bus 002 Device 004: ID 064f:0bd8 ABC-Systems AB CDE/FG

xm usb-add shows;

Usage: xm usb-add domain [host:bus.addr] [host:vendor_id:product_id]

Not sure what combo will work in this case.

However, I've read some notes regarding xm usb-attach.  What subset of  
Xen do I need for this command to show?

- aurf
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[CentOS] installing windows 2008 server( VM) on a centos xen server

[Agnello George]

 hi

I have a xen cent os (Dom0) .. i want to add a vm ( windows 2008 server ) ,
since i am using command line how do i see  the  the windows machine. boot
?? .. i am really confused here .
I have previous iinstalled centos ( VM)  , but that was command line based .


Can some one please direct me on this

-- 
Regards
Agnello D'souza
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Re: [CentOS] installing windows 2008 server( VM) on a centos xen server

[Vincent Li]

On 01/03/2011 09:40 AM, Agnello George wrote:

 hi

I have a xen cent os (Dom0) .. i want to add a vm ( windows 2008 
server ) , since i am using command line how do i see  the  the 
windows machine. boot ?? .. i am really confused here .
I have previous iinstalled centos ( VM)  , but that was command line 
based .


Can some one please direct me on this

--
Regards
Agnello D'souza



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There is no way to see the Windows VM booting. Just use the GUI 
Environment or VNC remotely.


--
Best Regards,

Vincent Li

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Re: [CentOS] installing windows 2008 server( VM) on a centos xen server

[Gabriel]

You can install virt-manager on the centos box, and then use it via ssh,
for example

 

ssh -X u...@centoshost.com

 

Then on the command line, run virt-manager, (you may need to install
xauth as well, but it works a charm)

 

From: centos-boun...@centos.org [mailto:centos-boun...@centos.org] On
Behalf Of Agnello George
Sent: 03 January 2011 14:40
To: CentOS mailing list; li...@yahoogroups.com
Subject: [CentOS] installing windows 2008 server( VM) on a centos xen
server

 

 hi

I have a xen cent os (Dom0) .. i want to add a vm ( windows 2008 server
) , since i am using command line how do i see  the  the windows
machine. boot ?? .. i am really confused here .  
I have previous iinstalled centos ( VM)  , but that was command line
based . 

Can some one please direct me on this 

-- 
Regards 
Agnello D'souza



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Re: [CentOS] installing windows 2008 server( VM) on a centos xen server

[Agnello George]

On Mon, Jan 3, 2011 at 8:14 PM, Gabriel gabr...@impactteachers.com wrote:

  You can install virt-manager on the centos box, and then use it via ssh,
 for example



 ssh –X u...@centoshost.com



 Then on the command line, run virt-manager, (you may need to install xauth
 as well, but it works a charm)





well i am not given permission to install GUI for the centos (dom0)  :(


-- 
Regards
Agnello D'souza
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Re: [CentOS] upgrading Centos-Xen when version 6 comes along

[Gabriel Tabares]

 Also, if you assign MACs to your VMs at installation time (I do, for
 DHCP- and DNS-related reasons), you should note that KVM MACs lives in
 a different namespace: 54:52:00:xx:xx:xx.

You can change the allocated MAC address by editing the files in 
/etc/libvirt/qemu .

Edit the mac address='54:52:00:19:f2:ef'/ section and you're all set.

I am not sure if you need to restart libvirtd after making the changes, 
as I have not got a machine I can test that at the moment.


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Re: [CentOS] upgrading Centos-Xen when version 6 comes along

[Gabriel Tabares]

 The biggest single up-front difference for me on CentOS machines was
 that KVM hosts default to NAT on a private bridge while Xen hosts
 default to straight bridging. Some network tweaks are necessary to get
 KVM hosts to live on a straight bridge.

Sorry, I forgot to add to this before.

If you want to use bridging in KVM you need to set up bridge interfaces 
on the host (br0 and so on) and assign the main IP address to that 
interface, instead of to the underlying physical one.

One more thing, if you assign a bridge to a VLAN interface, you do not 
need to add the VLAN on the guest, just treat it as a normal interface 
and the guest will take care of the tagging for you.

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