Don’t neglect the Virtual Machine hardware!
Here’s a quick cautionary tale of a client who let their Virtual Machine Hardware get quite a few cycles out of date. We were setting up a new node in an VMware EVC cluster and noticed that we were able to vMotion to the newest host but once on the newest host, the VM was trapped there. When trying to vMotion out to other hosts within the EVC, the vMotion checks were failing with CPU Mask failures.
What? This didn’t make sense. The hosts were already admitted into the EVC cluster. All the VMs should be happily moving around from host to host. Turns out the issue was with the Hardware Version. Many of the VMs were still on HW Version 4, 7 and 8. Once we upgraded the hardware versions to VMX-10, the machines were fluid again in the EVC. Of course, this was a major source of stress since in order to upgrade the VM Hardware, the machine needed to be powered off. (i.e downtime).
So when you have maintenance windows, be sure to not only upgrade those VMware Tools, but also be sure to keep the Hardware versions up to date (or at least close). You’ll be happy you did.