OK, I see 2 topic here that I want to comment upon:
_*PHP 5.3 and COS5*_
PHP 5.3 on COS5 is not that hard -- but the packages are named
*php53*, not /php5/ (but you probably already knew that)
-- NOTE: I did the update/upgrade AFTER installing QMT, and when
packages had to be uninstalled for replacement and YUM complained, I
just did an *rpm -e --nodeps* followed by the appropriate yum install.
Other than the web scripts, everything went well... NOT having a no-deps
option to YUM is its biggest flaw, IMHO -- but then again, it IS there
with rpm, so I guess I'm just being picky (and un-UNIX -- one tool to do
everything runs counter to the UNIX philosophy of each tool doing only 1
thing, and doing it well). The noted "break" in QMT is (obviously) only
in the web interfaces (vpopmail & squirrelmail in base QMT) -- and are
easily fixed by "patching" the php.ini to allow open tags. That is the
ONLY real issue that I am aware of in QMT and PHP53.
I know this because one of my mail servers (actually, my primary mail
server) is still running COS5 and PHP53 (I'm planning to upgrade to COS6
on Thursday (Boxing Day), as it is expected to be an otherwise slow day.
:) -- That server (actually, THIS server, as it is the one this mail
will come from) is COS 5.7 & PHP 5.3.3 and has been for a VERY LONG time
now.
_*Virtualization
*_While poo-poohed by many, I actually like the QEMU/KVM method of
managing VMs (I know Eric likes ProMox VE)... but my experience with VMs
has been excellent with Linux guests -- my only recommendation is to run
the newer SW as the VM manager (so COS6 as VM host, then COS 5 or COS6
-- or any other Linux -- as guest).
Where I have had performance issues was when I tried running Windoze on
KVM -- and it turned out it was the storage and network controllers that
were hanging me up. RHEL has a virtio driver for Windows that GREATLY
improves the storage I/O efficiency, and switching the NIC card
emulation to E1000 (I prefer it over the virtio) solved all of those
issues. I now successfully routinely deploy a Windows 2012 server (for
AD, local DNS, and DHCP only) and a Linux file server (for everything
else) on a COS6 VM Manager (running COS6 with QEMU/KVM).
If I have any issues with QEMU/KVM it would be that the tools to BUILD a
new VM don't offer all of the options that really exist (for example, to
make the disk image qcow2 vs. a raw image, I have to first create it as
a raw image, then convert it and manually change the drive type in the
manager.)... this isn't a HUGE issue, since I keep a "starter kit" of
qcow disk images on hand to "kick start" installs :)
Just my thoughts and experiences....
Dan
QMT DNS/Mirror Admin
PS: You might note that Eric and I often disagree on tech issues --
personally, I think this makes our project stronger, as we challenge
each other. I know that MY installations and procedures have been
improved because I take the time to "argue the point" with Eric -- which
makes me look at my decisions anew frequently, and re-evaluate my
opinions often. I suspect that he has altered an opinion or two based on
my input over the years... but that is pure speculation on my part :)
On 12/22/2013 1:27 PM, Eric Shubert wrote:
Hey Kahn,
First, I would try to avoid running anything other than the hypervisor
on bare iron. Run everything virtualized underneath it.
Generally speaking, KVM performs better with newer kernels. Older
kernels use 10-20% of a cpu when idle. With newer kernels, KVMs use
<0.5% cpu when idle.
I'm not sure exactly what the change is that provides this
improvement. It appears to have happened around 3.4 in the main kernel
versions, but it also appears that RedHat (and thus COS) has
backported this change to their 2.6.32 version. BL, COS6 runs well as
a KVM, but COS5 does not. I expect that both hypervisor and guests
need to be running the improved version of the kernel to realize this
improvement.
My virtualization platform of choice is ProxmoxVE. It provides a nice
web interface for management, and has been very reliable for me. I've
used versions 2.1-3.1. While PVE is debian based and uses .deb
packages, it uses a RedHat kernel, which give it the performance gains
mentioned.
The PVE kernel also provides OpenVZ container support, as does the web
interface. While COS5 guests don't run so well as KVMs, they run quite
nicely as OpenVZ containers. I won't go into the differences here, but
running just about anything linux based as an OpenVZ container should
work ok.
I should emphasize that the point is not that running COS5 as a KVM
*won't* work (it will), it's just that there's some overhead involved
that's been eliminated in more recent kernels. In fact, I've run COS5
as KVMs in production just fine for a period of time, on as little as
a dual-core 1.6GHz machine. It's fine so long as the horsepower's
available to run it (which it quite commonly is, as I've found most
servers to be severely overbuilt).
The only thing that bothers me with PVE is that beginning with 3.1
(which is the current release), they've introduced a subscription
based structure for their repos, sort of like RHEL. The cost isn't
excessive for small users, but it still rubs me the wrong way. They do
still provide a free repo, but all the latest changes aren't
guaranteed to be there. We'll see how things pan out in the long run.
I wouldn't be surprised to see a COS-type counterpart to PVE spring up
and provide all of the PVE software for free, only lagging slightly in
when it's released.
I should also probably mention that I started using virtualization
with VMware Server 1.0. After VMware discontinued VMware Server 2.0, I
began looking for something KVM based, and have been using PVE since
then. I realize that there is a free VMware version, but it's very
limited to certain enterprise grade hardware. I'm looking for
something more affordable that can run on generic hardware. VMware
undoubtedly is the leader in server virtualization, but RedHat is
making substantial gains in that arena.
VirtualBox has grown up out of Desktop Virtualization. It's a very
nice platform for virtualizing desktops, and I consider them the
leader in this arena. Desktop virtualization has much different needs
though, as desktops are used much differently than servers. I don't
look for VB to become a substantial player in the server
virtualization market.
Let me know if you have any further questions. I hope we'll get this
sort of info available on the new wiki at github in the future. There
is some virtualization info on the present wiki, but it's pretty
outdated.
Thanks for the questions.
--
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