What is EVC Mode ? It is a feature that permit to do live vMotion between host running different CPU generation but same family (like Haswell and Sandy bridge in the same cluster). Intel / AMD mixed hosts in a cluster will not support live vMotion anyway.

This is a feature that I’ve node enable very often. And each time you ask someone about it, he almost always told you that you must shutdown every virtual machine in the cluster to be able to activate it. Wrong !

Basically, there is two condition to be able to activate EVC Mode successfully:

  1. No virtual machine must be running on the most recent vsphere host (most recent CPU generation), even the Simplivity virtual controller must be shutdown !
  2. No VM must be using a CPU feature that is present on the CPU model on the last host

This feature is available at the cluster level and it does a CPU and VM assessment. Meaning that you will not be able to activate it if there is any incompatibility.

EVC mode

I’ve recently added a Simplivity CN3400 within a CN3000 cluster and one VM was set with some specific settings preventing the activation of EVC mode. We finally found it and it was an appliance made on a more recent vSphere host by a manufacturer (Bomgar in this case). Once the VM shutdown, the EVC mode was ready to activate!

Now you could start your cluster upgrade with confidence and without massive VM interruption!