EVC

[faruge]

Hi there,

A quick question for the more advanced gurus out there:

I have come across a customer that has a cluster running 5 hosts.  However, I noticed that the CPU chip set is different for 3 of the servers (A mixture of Broadwell, Ivy Bridge and Sandy Bridge).  HA and DRS is enabled in the cluster, however I noticed that EVC is disabled.  I thought I had an understanding that this is not a compatible scenario and would have prevented adding hosts that have a different chip set.  I also noticed that I can successfully vMotion a VM from a Broadwell CPU server to a Sandy Bridge CPU server without issue.

Running vSphere 6.5 (vCenter and Hosts)

Have I missed something here?

Thanks in advance.

Justin

[GayathriS]

You can vMotion to different host CPUs if they are in the same CPU family.  If they are in different CPU families (still have to be all Intel or all AMD) you can still do vMotions but you have to enable VMWare EVC

If the CPU's are in the same CPU family (E.g. 2.3 GHZ Intel Sandy Bridge to a 2.8GHZ Intel Sandy Bridge) then you can vMotion between those hosts. Once you get out of the same family it wont work (e.g. Intel Sandy Bridge to AMD Magny Cours). You may have success if the processor family are one revision away but it's not recommended.

Below is the best article :

VMware Knowledge Base

Please consider marking this answer as correct and helpful if this helps you.

regards

Gayathri

[IRIX201110141]

If you start a VM on your oldest Server(Sandybridge) you can perform a vMotion to all newer servers and also backwards because Intel CPUs never have dropped a CPU feature in the past.

If you start a VM on your latest Servers (Broadwell) you cant perform a vMotion back to Sandybridge because of missing CPU features.  The VM took the CPU features when you powered it on... and hold these settings as long the VM is running (a GuestOS reboot doesnt change anything there).

If you start remediation aginst Meltdown and Spectre than the game may change especially if you start with your old hosts.

But Bestpractice is to enable EVC because it makes live much easier when having mixed generations of servers within a cluster or datacenter.

Regards,

Joerg

[StephenMoll]

If the OP moves onto vSphere 6.7, they would be able to use "Per VM EVC" settings too.