Will VM migrations still work with this cpu configuration

[schoeppi]

All the 3 nodes in our current proxmox production cluster have a AMD EPYC 7302P 16-Core cpu. Now we have to replace one node with a machine which has a AMD EPYC 9124 cpu.

Will VM migrations work with this different cpu setup without restarting the VMs if a VM is moved from a node to another node with a different cpu?

We have another cluster where one nodes cpu is different. On this clusters VMs can be migrated between the nodes but I have to restart the VMs on the new node when it is the node with the different cpu modell. This is our test cluster, therefore this is no big problem, but we want to avoid such scenario on our production cluster if possible .

Do others have clusters with mixed cpu's from AMD and can tell how such a setup is working and VMs can still be migrated without downtime?

 

[weehooey-bh]

They might. I am not familiar with these processors' differences but adjusting the VM's CPU type should get you there.

When provisioning the CPU, do you set the type to host? If so, try using one of the EPYC-Rome-* types (older models). If those do not work, the x86-64-v2-AES should.

Essentially, you want to present the lowest common denominator of CPU feature sets to the VM. This way, the VMs will see the same virtual processor no matter which CPU is on the host, and rebooting the VM should be avoided.

 

[schoeppi]

Currently we are using "max" as cpu typ for all our VMs :-( :

...
cpu: max
...

I know, thats the worst solution, but e.g. KeyCloak, which we use in some VMs, does not start if cpu typ is set to another value :-(. We had host before and I'd really like to enable it again, but for KeyCloak and because I like to have not that much different VM configuration variants we are using this setting currently.

Maybe its time to think about different configuration profiles and therefore for different templates for different type of VMs.

How do you handle this? Do you have diffenent templates with different settings also for the virtualized hardware or do you also try to keep the settings the same for all your VMs?

 

[Weehooey-HSS]

Hmm, from my limited knowledge of KeyCloak, it requires the CPU to support SSE4.2. This should be supported on your lowest CPU. However, you said it was not working when set to "Host." Have you tried setting the CPU type to EPYC?

Can you run a

lscpu

on your host and check the flags?