All of our hosts are configured using the same hardware. As a best-practice, we do enable EVC on the cluster.
We created a new cluster, and enabled EVC mode for AMD Opteron Generation 1. When attempting to add a host (with running VMs) to the new cluster, we get an error message stating "the host cannot be admitted to the cluster's current EVC mode. Powered-on or suspended VMs on the host may be using features hidden by that mode". As a workaround, I disabled EVC on the cluster, added the host, and then enabled EVC. There were no errors when doing this. I was also able to successfully disable/enable EVC with running VMs within the cluster.
It was my understanding that in order to change the EVC mode (raise/lower, enable/disable) you did need to power cycle the VMs. Are there any issues in doing it the way I have described above?