So I upgraded vCenter from 5.1 to 5.5u3b, I disabled HA/DRS before the upgrade and when I re-enabled HA post upgrade on the cluster (ESXi5.1) 4 hosts in the cluster started to attempt HA failover. This happened at the exact same time the HA agents were being installed on all the hosts in the cluster?
Nothing actually failed over, but I got a bunch of "vSphere HA virtual machine failover failed" cluster level alarms.
The cluster is a mix of dell r710 and dell r720 hosts, and it was only the r720 hosts that this happened on. Yet I have another cluster with just r720 hosts where this didn't happen. They all run ESXI 5.1 and are all on the same firmware/BIOS etc.
Since it happened as the HA agent was being installed on the all the hosts in the cluster, I am assuming it was some kind of glitch? I haven't found any KB articles relating to it.
Cheers,