Mixed CPU HVM Cluster

[omar_medhat98]

Hello everyone,

I'd like to ask if mixing cpu models is supported in the same cluster.

Of course what I mean is mixing intel CPUs .. Specifically using Gen 9 server with xeon v4 and Gen 10 with xeon scalable.

Would live migration or any other features affected by this setup

I know it's not recommended but I have a customer who needs to use his Gen 9 in the setup.

Thanks in advance.

[Arnout_Verbeken]

To start, at this moment we officially support only 2 Gen9 servers: DL360 Gen9 and DL380 Gen9.
Other models will probably work fine, but should not be used in production as we will not give you any support on those servers.
See https://support.hpe.com/hpesc/public/docDisplay?docId=sd00006551en_us&page=GUID-EA7C0803-E66B-4B17-B994-30D4025A258F.html for the complete list.

Mixing CPU models - equivalent to VMware EVC -  in supported.  It should in theory even work between AMD and Intel CPU's (but I have not tested this).
When creating/editing  a cluster, you can specify the "CPU Model".  We recommend setting the CPU Model on "host-passhtrough", which is the default.

"Host-passthrough" will make sure that VM's can migrate to any host in the cluster, taking into account the different feature sets of the different CPU's in the cluster.  So if you mix CPU's, the common feature set between all those CPU's is used.

You can also set the CPU Model to a specific CPU-generation (Skylake, IceLake,....) like you would do in Vmware EVC to take full control of this setting yourself.  But we recommend to use the default "host-passthrough".

Note that there was a bug in 8.0.9 that would prevent VM's to boot when setting the CPU Model yourself.  I have not yet verified if this is solved in 8.0.10.
Note that a change to this setting will only take effect after a power cycle of the VM's.
You can verify if your VM can be migrated to all hosts in the cluster by verifying the xml of the VM.  It should contain "migratable=on".

 <cpu mode='host-passthrough' check='none' migratable='on'>
    <feature policy='disable' name='vmx'/>
    <feature policy='disable' name='x2apic'/>
    <numa>
      <cell id='0' cpus='0-31' memory='4194304' unit='KiB' memAccess='shared'/>
    </numa>
  </cpu>

 When migratable='on' is set, libvirt ensures that the CPU configuration exposed to the guest VM only includes CPU features that are migratable. This means it excludes CPU features that are specific to the host's hardware and might not be available on other hosts in a cluster.