Is live migration possible between EPYC 7352 and 9XXX?

[peterge]

We are planning to add a new hypervisor to our cluster. Three existing nodes have an AMD EPYC 7352 CPU and now we are unsure if we should go with the latest EPYC 9XXX processor or if we should stick with EPYC 7352 for the new server.

I have already tested the migration from EPYC 7352 to Ryzen 9 7950X and vice versa, it does work from EPYC to RYZEN but it doesnt work from RYZEN to EPYC (the debian VM freezes when I migrate from RYZEN to EPYC). Our goal is to be able to migrate instantly.

Could someone link any resources that confirms my question or has anyone tested this with the exact same hardware before?


The reason for this upgrade is because we have 2 sites, and we would like to have servers which allow instant migration between both hypervisors on both sites to do updates, etc.

 

[alyarb]

On each VM, set the virtual CPU type to the closest common ancestor to all the processors in the cluster.

In this example I would probably choose EPYC-Rome.

If you try to migrate a running VM to a host lacking any of the enabled instruction set extensions, the VM will crash.

Your Ryzen cores are Zen 4, and feature AVX512. The EPYC 7352 is Zen 2 and does not feature AVX512.

 

[peterge]

The closest common ancestor for EPYC 7352 and 9XXX would be EPYC-Rome.

What would it be for EPYC 7352 and Ryzen 9 7950X?

 

[alyarb]

Same, it sounds like Zen 2 is the oldest in your cluster. All of your VMs should be configured to expect a Zen 2 host, and the only thing they will not have enabled is AVX512.

If you know for a fact you have a specific need for AVX512 (hint: you don't, your prod hosts do not have it) then you would need to upgrade all of your hosts to EPYC 9000 and then set the virtual CPU type to "host."

 

[peterge]

Related wiki page: https://pve.proxmox.com/wiki/Qemu/KVM_Virtual_Machines#_cpu_type