VMotion between two different clusters with different CPUs (Same family though!) Without Permanent EVC Clusters

Have you ever wanted to VMotion a VM from lets say a Nehalem based cluster to a Westmere based cluster but got that pesky error message saying the CPUs aren’t compatible? Do you have using EVC mode for clusters?

I’ve used this method in the past to move a couple thousand QA/Dev Linux/Windows VMs without downtime.

We are essentially creating a Jump EVC cluster that will allow you to hop VMs from nehalem hardware to westmere hardware while online. 

• Create a new cluster at based at the lowest CPU EVC level that you are using.. My case was Nehalem. 
• Place a Nehalem host and a Westmere host into Maintenance mode. 
• Move both hosts into the EVC Cluster.. 
• Remove them from Maintenance mode. 
• VMotion a VM from your Nehalem Cluster to the Nehalem server in the EVC Cluster.
• Then VMotion it to the Westmere blade inside the same cluster. 
• Then VMotion it to it’s final resting place in the Westmere non-EVC cluster.

A few things to mention.

Obviously both hosts need to be on the same VMotion subnet for this to work.

Some of the newer processors are coming with AES-NI pre-enabled in the BIOS which makes this process moot. (Unless you go into each server’s bios and disabled AES-NI.

Ensure DRS is disabled in your EVC cluster – this gives you the most control over where the VM will go so you don’t screw anything up.

I do not suggest you do this in a production environment unless you’re feeling like a cowboy.. I cannot take blame for you blowing up your VMs in the very unlikely event that you do something wrong.

One more caveat is that if you look at the processors inside the VM after the move they will still show as the original processors.. This will not cause a problem – just reboot the VM when you have a patching window and/or maintenance windows.