[ovirt-users] Re: About the vm memory limit

2021-09-25 Thread Tommy Sway 
In fact, I am very interested in the part you mentioned, because my environment 
is running relational database, which usually requires a large amount of 
memory, 

and some systems clearly need to configure HUGEPAGE memory (such as Oracle). 

 

Could you elaborate on some technical details about the management of huge page 
memory? And the difference between 4.3 and 4.4 in this respect? 

 

Thank you very much!

 

 

 

From: Strahil Nikolov  
Sent: Saturday, September 25, 2021 5:32 PM
To: Tommy Sway 
Subject: Re: [ovirt-users] About the vm memory limit

 

It depends on the numa configuration of the host.

 

If you have 256G per CPU, it's best to stay into that range.

 

Also, consider disabling transparent huge pages on the host & VM.

 

Since 4.4 Regular Huge Pages (do not confuse them with THP) can be used on the 
Hypervisors, while on 4.3 there were some issues but I can't provode any 
details.

 

Best Regards,

Strahil Nikolov

On Fri, Sep 24, 2021 at 6:40, Tommy Sway

mailto:sz_cui...@163.com> > wrote:

I would like to ask if there is any limit on the memory size of virtual 
machines, or performance curve or something like that?

As long as there is memory on the physical machine, the more virtual machines 
the better?

 

In our usage scenario, there are many virtual machines with databases, and 
their memory varies greatly. 

For some virtual machines, 4G memory is enough, while for some virtual 
machines, 64GB memory is needed.

 

I want to know what is the best use of memory for a virtual machine, since the 
virtual machine is just a QEMU emulation process on a physical machine, and I 
worry that it is not using as much memory as a physical machine. Understand 
this so that we can develop guidelines for optimal memory usage scenarios for 
virtual machines.

 

Thank you!

 

 

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[ovirt-users] Re: About the vm memory limit

2021-09-25 Thread Tommy Sway 
transparent huge pages are not used on vm and physical host.

 

But, can I enable hugepage memory on  virtual machines but not on a physical 
machine?

For database running on vm, and it needs to config hugepage.

 

 

From: Strahil Nikolov  
Sent: Saturday, September 25, 2021 5:32 PM
To: Tommy Sway 
Subject: Re: [ovirt-users] About the vm memory limit

 

It depends on the numa configuration of the host.

 

If you have 256G per CPU, it's best to stay into that range.

 

Also, consider disabling transparent huge pages on the host & VM.

 

Since 4.4 Regular Huge Pages (do not confuse them with THP) can be used on the 
Hypervisors, while on 4.3 there were some issues but I can't provode any 
details.

 

Best Regards,

Strahil Nikolov

On Fri, Sep 24, 2021 at 6:40, Tommy Sway

mailto:sz_cui...@163.com> > wrote:

I would like to ask if there is any limit on the memory size of virtual 
machines, or performance curve or something like that?

As long as there is memory on the physical machine, the more virtual machines 
the better?

 

In our usage scenario, there are many virtual machines with databases, and 
their memory varies greatly. 

For some virtual machines, 4G memory is enough, while for some virtual 
machines, 64GB memory is needed.

 

I want to know what is the best use of memory for a virtual machine, since the 
virtual machine is just a QEMU emulation process on a physical machine, and I 
worry that it is not using as much memory as a physical machine. Understand 
this so that we can develop guidelines for optimal memory usage scenarios for 
virtual machines.

 

Thank you!

 

 

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[ovirt-users] Re: why cannot set the power management proxy server ?

2021-09-25 Thread Tommy Sway 
Thank you very much!

I have read your document. The article mentioned that LANPLUS enhances the 
security of communication, but it did not elaborate on what LANPLUS is. 

I want to know what technology it is.

 

 

 

 

From: users-boun...@ovirt.org  On Behalf Of Strahil 
Nikolov via Users
Sent: Saturday, September 25, 2021 5:28 PM
To: Tommy Sway ; 'users' 
Subject: [ovirt-users] Re: why cannot set the power management proxy server ?

 

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/fence_configuration_guide/s1-software-fence-ipmi-ca

 

True or 1. If blank, then value is False. It is recommended that you enable 
Lanplus to improve the security of your connection if your hardware supports it.

 

Most probably the hardware doesn't support with reduced security (lanplus=False 
is the default).

 

Best Regards,

Strahil Nikolov

On Fri, Sep 24, 2021 at 6:12, Tommy Sway

mailto:sz_cui...@163.com> > wrote:

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[ovirt-users] Reinstall without dataloss

2021-09-25 Thread hans 
Hi all,

I am new here, been searching the mailing list on a regular base when I 
encountered problems and till now I always was able to keep the system up & 
running.
As said... till now...
I have oVirt at home, and I have about 7 vm's running on it. Lately I have had 
some troubles with my electricity, which results in a complete power outage on 
a irregular base.
Yesterday I had a power outage which left the system unbootable with the 
following errors:

error: ../../grub-core/loader/i386/pc/linux.c:170:invalid magic number.
error: ../../grub-core/loader/i386/pc/linux.c:1418:you need to load the kernel 
first.
Press any key to continue

Normally this can be solved following  
https://access.redhat.com/solutions/5829141, but his time also the files in 
/boot had a size of 0 bytes.  So basically i did not have a working kernel on 
the system anymore.

https://www.thegeekdiary.com/centos-rhel-7-how-to-install-kernel-from-rescue-mode/
 does work for CentOS 8 also, but the ovirt 4.8 iso does not have the same 
directory structure. Using CentOS 8 installs a kernel, but not a bootable 
system.

Is there a way i can start the installer in troubleshooting mode so I can 
reinstall just the kernel on the system?
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[ovirt-users] Re: why cannot set the power management proxy server ?

2021-09-25 Thread Strahil Nikolov via Users 
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/fence_configuration_guide/s1-software-fence-ipmi-ca
True or 1. If blank, then value is False. It is recommended that you enable 
Lanplus to improve the security of your connection if your hardware supports it.
Most probably the hardware doesn't support with reduced security (lanplus=False 
is the default).
Best Regards,Strahil Nikolov
 
 
  On Fri, Sep 24, 2021 at 6:12, Tommy Sway wrote:   
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