I had a fun day resolving a licensing issue for a client. This one was a little different than I had seen in the past. The cluster is question is an eight node cluster running ESX 3.5. The error message that I received when trying to perform a vMotion was “Unable to migrate from HostA to HostB: Virtual machine has 2 virtual CPUs, but the host only supports 1. The number of virtual CPU’s may be limited by the guest OS selected for the virtual machine or by the licensing for the host.”
When you hear the term “host” when talking about virtual environment, what is the first thing you think of? For me, the answer is simple, a host is an appliance. For years now I have been standing on my soap box and preaching the power and fundamentals of automation in building and configuring your virtual environment. I came across a thread on the VMware VMTN Community Forum where a concerned individual was in a position that he was going to have to rebuild his host from scratch. What he did to get himself into this position was to run a hardening script on the host and then the host became broken and unusable. This person was concerned that he did not have a backup of the host and was looking for a way to rollback.