Re: [ovirt-users] Mixing CPU types

[Matthew Trent]

Sure would be a nice feature, though! It would simplify things for those of us 
who build out of re-purposed Windows servers (still a lot of life left in them 
for Linux applications!) and end up with a mix of CPUs. For most of my VMs I 
don't need the latest and greatest CPU features, but being able to consolidate 
my hosts into fewer clusters would be really useful.

Like you said, oVirt already allows mixing CPU generations by selecting the 
lowest common denominator CPU type -- as long as you stick to Intel or AMD. 
It's a similar scenario, and the KVM stuff seems well established. Just expose 
some additional "generic" CPU types, per the KVM docs, and allow mixed 
clusters...

--
Matthew Trent
Network Engineer
Lewis County IT Services
360.740.1247 - Helpdesk
360.740.3343 - Direct line


From: Martin Polednik <mpoled...@redhat.com>
Sent: Wednesday, February 3, 2016 11:43 PM
To: Matthew Trent
Cc: Yaniv Kaul; users@ovirt.org
Subject: Re: [ovirt-users] Mixing CPU types

- Original Message -
> From: "Matthew Trent" <matthew.tr...@lewiscountywa.gov>
> To: "Yaniv Kaul" <yk...@redhat.com>
> Cc: users@ovirt.org
> Sent: Wednesday, February 3, 2016 8:10:35 PM
> Subject: Re: [ovirt-users] Mixing CPU types
>
> ?Actually it works great! It's been supported by KVM for a while now. I had
> one Proxmox cluster with a mix of AMD and Intel and migrated KVM VM's
> between them frequently. OpenStack (KVM) and VMWare support this as well.
>
>
> The trick is to expose a virtual CPU with a common set of features to the
> VMs. KVM handles the rest. From the KVM FAQ:
>
> http://www.linux-kvm.org/page/FAQ#Does_KVM_support_live_migration_from_an_AMD_host_to_an_Intel_host_and_back.3F

That is pretty much what libvirt does. The sandy-bridge, haswell and other
cpu's that we expose are not really a CPUs, but sets of flags (called
baseline CPUs in libvirt's terminology).

Afaik there should be no issue running cluster with both CPU vendors,
the problem is lack of testing on devel side as we mostly run
single vendor clusters everywhere.

> "Does KVM support live migration from an AMD host to an Intel host and back?
>
>
> Yes. There may be issues on 32-bit Intel hosts which don't support NX (or
> XD), but for 64-bit hosts back and forth migration should work well.
> Migration of 32-bit guests should work between 32-bit hosts and 64-bit
> hosts. If one of your hosts does not support NX, you may consider disabling
> NX when starting the guest on a NX-capable system. You can do it by passing
> "-cpu qemu64,-nx" parameter to the guest."
>
> --
> Matthew Trent
> Network Engineer
> Lewis County IT Services
> 360.740.1247 - Helpdesk
> 360.740.3343 - Direct line
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Re: [ovirt-users] Mixing CPU types

[Martin Polednik]

- Original Message -
> From: "Matthew Trent" <matthew.tr...@lewiscountywa.gov>
> To: "Yaniv Kaul" <yk...@redhat.com>
> Cc: users@ovirt.org
> Sent: Wednesday, February 3, 2016 8:10:35 PM
> Subject: Re: [ovirt-users] Mixing CPU types
> 
> ?Actually it works great! It's been supported by KVM for a while now. I had
> one Proxmox cluster with a mix of AMD and Intel and migrated KVM VM's
> between them frequently. OpenStack (KVM) and VMWare support this as well.
> 
> 
> The trick is to expose a virtual CPU with a common set of features to the
> VMs. KVM handles the rest. From the KVM FAQ:
> 
> http://www.linux-kvm.org/page/FAQ#Does_KVM_support_live_migration_from_an_AMD_host_to_an_Intel_host_and_back.3F

That is pretty much what libvirt does. The sandy-bridge, haswell and other
cpu's that we expose are not really a CPUs, but sets of flags (called
baseline CPUs in libvirt's terminology).

Afaik there should be no issue running cluster with both CPU vendors,
the problem is lack of testing on devel side as we mostly run
single vendor clusters everywhere.
 
> "Does KVM support live migration from an AMD host to an Intel host and back?
> 
> 
> Yes. There may be issues on 32-bit Intel hosts which don't support NX (or
> XD), but for 64-bit hosts back and forth migration should work well.
> Migration of 32-bit guests should work between 32-bit hosts and 64-bit
> hosts. If one of your hosts does not support NX, you may consider disabling
> NX when starting the guest on a NX-capable system. You can do it by passing
> "-cpu qemu64,-nx" parameter to the guest."
> 
> --
> Matthew Trent
> Network Engineer
> Lewis County IT Services
> 360.740.1247 - Helpdesk
> 360.740.3343 - Direct line
> ________
> From: Yaniv Kaul <yk...@redhat.com>
> Sent: Tuesday, February 2, 2016 2:17 PM
> To: Matthew Trent
> Cc: users@ovirt.org
> Subject: Re: [ovirt-users] Mixing CPU types
> 
> 
> 
> On Mon, Feb 1, 2016 at 9:13 PM, Matthew Trent
> <matthew.tr...@lewiscountywa.gov<mailto:matthew.tr...@lewiscountywa.gov>>
> wrote:
> Though our new oVirt setup is better in most ways, cross-CPU-type migration
> is one of the features I miss from Proxmox. KVM supports mixed-CPU migration
> for a while now, even between AMD and Intel.
> 
> http://www.linux-kvm.org/page/Migration
> 
> I highly doubt the above works in real life scenarios.
> Y.
> 
> 
> 
> I'm using a bunch of re-purposed servers with a mix of AMD and Intel. I
> separate them into clusters, as noted, but it sure would be nice to be able
> to live migrate between them. :)
> 
> --
> Matthew Trent
> Network Engineer
> Lewis County IT Services
> 
> > Hi Rene,
> >
> > Thank you very much for coming back to me.
> >
> > That's perfect then and answers my questions exactly.
> >
> > Much appreciated.
> >
> > Regards.
> >
> >Neil Wilson.
> >
> >
> >On Wed, Jan 27, 2016 at 1:57 PM, René Koch  >rk-it.at<http://rk-it.at>> wrote:
> >>
> >> Hi Neil,
> >>
> >> You can mix cpu types (but not AMD and Intel) if you leave the cluster
> >> level at the lowest cpu level.
> >> I personally don't mix cpu levels if possible, but instead create own
> >> clusters for each cpu type in order to be able to use the newest cpu
> >> features...
> >>
> >>
> >> Regards,
> >> René
> >>
> >>
> >> On 01/27/2016 12:53 PM, Neil wrote:
> >>
> >> Hi guys,
> >>
> >> I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and I
> >> need to add a new host for more RAM and vCPU's, however the new Xeon e5
> >> cpu's are Haswell based.
> >>
> >> Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I be
> >> able to migrate between my hosts?
> >>
> >> I'm guessing that for this to work I'll need to leave my "CPU type" set to
> >> Sandy Bridge, will the Haswell based CPU be compatible with my cluster,
> >> but
> >> just run without any Haswell type features?
> >>
> >> Apologies if this is a dumb question or if it's been answered before.
> >>
> >> Thank you.
> >>
> >> Regards.
> >>
> >> Neil Wilson
> >>
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> 
> 
> 
> 
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Re: [ovirt-users] Mixing CPU types

[Matthew Trent]

?Actually it works great! It's been supported by KVM for a while now. I had one 
Proxmox cluster with a mix of AMD and Intel and migrated KVM VM's between them 
frequently. OpenStack (KVM) and VMWare support this as well.


The trick is to expose a virtual CPU with a common set of features to the VMs. 
KVM handles the rest. From the KVM FAQ:

http://www.linux-kvm.org/page/FAQ#Does_KVM_support_live_migration_from_an_AMD_host_to_an_Intel_host_and_back.3F


"Does KVM support live migration from an AMD host to an Intel host and back?


Yes. There may be issues on 32-bit Intel hosts which don't support NX (or XD), 
but for 64-bit hosts back and forth migration should work well. Migration of 
32-bit guests should work between 32-bit hosts and 64-bit hosts. If one of your 
hosts does not support NX, you may consider disabling NX when starting the 
guest on a NX-capable system. You can do it by passing "-cpu qemu64,-nx" 
parameter to the guest."

--
Matthew Trent
Network Engineer
Lewis County IT Services
360.740.1247 - Helpdesk
360.740.3343 - Direct line

From: Yaniv Kaul <yk...@redhat.com>
Sent: Tuesday, February 2, 2016 2:17 PM
To: Matthew Trent
Cc: users@ovirt.org
Subject: Re: [ovirt-users] Mixing CPU types



On Mon, Feb 1, 2016 at 9:13 PM, Matthew Trent 
<matthew.tr...@lewiscountywa.gov<mailto:matthew.tr...@lewiscountywa.gov>> wrote:
Though our new oVirt setup is better in most ways, cross-CPU-type migration is 
one of the features I miss from Proxmox. KVM supports mixed-CPU migration for a 
while now, even between AMD and Intel.

http://www.linux-kvm.org/page/Migration

I highly doubt the above works in real life scenarios.
Y.



I'm using a bunch of re-purposed servers with a mix of AMD and Intel. I 
separate them into clusters, as noted, but it sure would be nice to be able to 
live migrate between them. :)

--
Matthew Trent
Network Engineer
Lewis County IT Services

> Hi Rene,
>
> Thank you very much for coming back to me.
>
> That's perfect then and answers my questions exactly.
>
> Much appreciated.
>
> Regards.
>
>Neil Wilson.
>
>
>On Wed, Jan 27, 2016 at 1:57 PM, René Koch rk-it.at<http://rk-it.at>> wrote:
>>
>> Hi Neil,
>>
>> You can mix cpu types (but not AMD and Intel) if you leave the cluster
>> level at the lowest cpu level.
>> I personally don't mix cpu levels if possible, but instead create own
>> clusters for each cpu type in order to be able to use the newest cpu
>> features...
>>
>>
>> Regards,
>> René
>>
>>
>> On 01/27/2016 12:53 PM, Neil wrote:
>>
>> Hi guys,
>>
>> I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and I
>> need to add a new host for more RAM and vCPU's, however the new Xeon e5
>> cpu's are Haswell based.
>>
>> Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I be
>> able to migrate between my hosts?
>>
>> I'm guessing that for this to work I'll need to leave my "CPU type" set to
>> Sandy Bridge, will the Haswell based CPU be compatible with my cluster, but
>> just run without any Haswell type features?
>>
>> Apologies if this is a dumb question or if it's been answered before.
>>
>> Thank you.
>>
>> Regards.
>>
>> Neil Wilson
>>
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Re: [ovirt-users] Mixing CPU types

[Yaniv Kaul]

On Mon, Feb 1, 2016 at 9:13 PM, Matthew Trent <
matthew.tr...@lewiscountywa.gov> wrote:

> Though our new oVirt setup is better in most ways, cross-CPU-type
> migration is one of the features I miss from Proxmox. KVM supports
> mixed-CPU migration for a while now, even between AMD and Intel.
>
> http://www.linux-kvm.org/page/Migration


I highly doubt the above works in real life scenarios.
Y.


>
> I'm using a bunch of re-purposed servers with a mix of AMD and Intel. I
> separate them into clusters, as noted, but it sure would be nice to be able
> to live migrate between them. :)
>
> --
> Matthew Trent
> Network Engineer
> Lewis County IT Services
>
> > Hi Rene,
> >
> > Thank you very much for coming back to me.
> >
> > That's perfect then and answers my questions exactly.
> >
> > Much appreciated.
> >
> > Regards.
> >
> >Neil Wilson.
> >
> >
> >On Wed, Jan 27, 2016 at 1:57 PM, René Koch  wrote:
> >>
> >> Hi Neil,
> >>
> >> You can mix cpu types (but not AMD and Intel) if you leave the cluster
> >> level at the lowest cpu level.
> >> I personally don't mix cpu levels if possible, but instead create own
> >> clusters for each cpu type in order to be able to use the newest cpu
> >> features...
> >>
> >>
> >> Regards,
> >> René
> >>
> >>
> >> On 01/27/2016 12:53 PM, Neil wrote:
> >>
> >> Hi guys,
> >>
> >> I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and
> I
> >> need to add a new host for more RAM and vCPU's, however the new Xeon e5
> >> cpu's are Haswell based.
> >>
> >> Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I
> be
> >> able to migrate between my hosts?
> >>
> >> I'm guessing that for this to work I'll need to leave my "CPU type" set
> to
> >> Sandy Bridge, will the Haswell based CPU be compatible with my cluster,
> but
> >> just run without any Haswell type features?
> >>
> >> Apologies if this is a dumb question or if it's been answered before.
> >>
> >> Thank you.
> >>
> >> Regards.
> >>
> >> Neil Wilson
> >>
> ___
> Users mailing list
> Users@ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
>
>
>
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Re: [ovirt-users] Mixing CPU types

[Matthew Trent]

Though our new oVirt setup is better in most ways, cross-CPU-type migration is 
one of the features I miss from Proxmox. KVM supports mixed-CPU migration for a 
while now, even between AMD and Intel.

http://www.linux-kvm.org/page/Migration

I'm using a bunch of re-purposed servers with a mix of AMD and Intel. I 
separate them into clusters, as noted, but it sure would be nice to be able to 
live migrate between them. :)

--
Matthew Trent
Network Engineer
Lewis County IT Services

> Hi Rene,
>
> Thank you very much for coming back to me.
>
> That's perfect then and answers my questions exactly.
>
> Much appreciated.
> 
> Regards.
>
>Neil Wilson.
>
>
>On Wed, Jan 27, 2016 at 1:57 PM, René Koch  wrote:
>>
>> Hi Neil,
>>
>> You can mix cpu types (but not AMD and Intel) if you leave the cluster
>> level at the lowest cpu level.
>> I personally don't mix cpu levels if possible, but instead create own
>> clusters for each cpu type in order to be able to use the newest cpu
>> features...
>>
>>
>> Regards,
>> René
>>
>>
>> On 01/27/2016 12:53 PM, Neil wrote:
>>
>> Hi guys,
>>
>> I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and I
>> need to add a new host for more RAM and vCPU's, however the new Xeon e5
>> cpu's are Haswell based.
>>
>> Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I be
>> able to migrate between my hosts?
>>
>> I'm guessing that for this to work I'll need to leave my "CPU type" set to
>> Sandy Bridge, will the Haswell based CPU be compatible with my cluster, but
>> just run without any Haswell type features?
>>
>> Apologies if this is a dumb question or if it's been answered before.
>>
>> Thank you.
>>
>> Regards.
>>
>> Neil Wilson
>>
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Re: [ovirt-users] Mixing CPU types

[René Koch]

Hi Neil,

You can mix cpu types (but not AMD and Intel) if you leave the cluster 
level at the lowest cpu level.
I personally don't mix cpu levels if possible, but instead create own 
clusters for each cpu type in order to be able to use the newest cpu 
features...



Regards,
René


On 01/27/2016 12:53 PM, Neil wrote:

Hi guys,

I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, 
and I need to add a new host for more RAM and vCPU's, however the new 
Xeon e5 cpu's are Haswell based.


Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will 
I be able to migrate between my hosts?


I'm guessing that for this to work I'll need to leave my "CPU type" 
set to Sandy Bridge, will the Haswell based CPU be compatible with my 
cluster, but just run without any Haswell type features?


Apologies if this is a dumb question or if it's been answered before.

Thank you.

Regards.

Neil Wilson


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[ovirt-users] Mixing CPU types

[Neil]

Hi guys,

I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and I
need to add a new host for more RAM and vCPU's, however the new Xeon e5
cpu's are Haswell based.

Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I be
able to migrate between my hosts?

I'm guessing that for this to work I'll need to leave my "CPU type" set to
Sandy Bridge, will the Haswell based CPU be compatible with my cluster, but
just run without any Haswell type features?

Apologies if this is a dumb question or if it's been answered before.

Thank you.

Regards.

Neil Wilson
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Re: [ovirt-users] Mixing CPU types

[Neil]

Hi Rene,

Thank you very much for coming back to me.

That's perfect then and answers my questions exactly.

Much appreciated.

Regards.

Neil Wilson.







On Wed, Jan 27, 2016 at 1:57 PM, René Koch  wrote:

> Hi Neil,
>
> You can mix cpu types (but not AMD and Intel) if you leave the cluster
> level at the lowest cpu level.
> I personally don't mix cpu levels if possible, but instead create own
> clusters for each cpu type in order to be able to use the newest cpu
> features...
>
>
> Regards,
> René
>
>
> On 01/27/2016 12:53 PM, Neil wrote:
>
> Hi guys,
>
> I currently have an oVirt 3.5 cluster with Sandy Bridge Xeon CPU's, and I
> need to add a new host for more RAM and vCPU's, however the new Xeon e5
> cpu's are Haswell based.
>
> Can I mix CPU types (Haswell and Sandy Bridge) in my cluster and will I be
> able to migrate between my hosts?
>
> I'm guessing that for this to work I'll need to leave my "CPU type" set to
> Sandy Bridge, will the Haswell based CPU be compatible with my cluster, but
> just run without any Haswell type features?
>
> Apologies if this is a dumb question or if it's been answered before.
>
> Thank you.
>
> Regards.
>
> Neil Wilson
>
>
> ___
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>
>
>
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