I have just installed a new 3 node cluster with vCenter Server Appliance 5.5 build 2001466. 2 ESXi nodes are 5.5 build 206810 and one is 5.5 build 1746018. The servers are Dell R620s.
During testing, I discovered that the "Host hardware power status" alarm will not consistently alert if I turn off A side power or B side power in the rack (meaning only one of the two power supplies in each ESXi host would have power).
I have tested each host one 1 PSU several times and the alarm would only alert about 20% of the time. In the case where a host is running on only 1 PSU and the alert failed to trip I checked under host > hardware status > sensors > power > ps1/ps2 > power supply AC lost and these sensors were both in the 'deassert' state which indicates that ESXi still thought both PSUs had power, so the root problem appears to be that ESXi cannot accurately monitor the status of the PSUs.
Since these systems are in a lights out datacenter I need to be able to rely on alerts in the event of a power or power supply failure so I can correct those problems before they impact my production environment.
I am wondering how I can fix this.