I had been repeatedly receiving a vCenter alarm from two of our new hosts for the last 3 or 4 days, both reporting that vmnic0 had lost connectivity. The initial investigation confirmed that the physical NIC was up and passing traffic. A review of the host logs showed no signs of an error and the physical upstream switch had no record of the link going down.
Previous Status: Green
New Status: Red
([Event alarm expression: Lost Network Connectivity; Status = Red] OR [Event alarm expression: Restored network connectivity to portgroups; Status = Green] OR [Event alarm expression: Lost Network Connectivity to DVPorts; Status = Red] OR [Event alarm expression: Restored Network Connectivity to DVPorts; Status = Green])
Lost network connectivity on virtual switch “vSwitch0″. Physical NIC vmnic0 is down. Affected portgroups:”Vmotion”, “Management Network”.
The alert was reporting that the loss of connectivity was affecting two portgroups which didn’t even have this pNic as its active adapter. The portgroups that were set with this adapter as active were not listed.
It then became apparent that the alerts were being sent exactly 1 hour apart. Smelling a rat I’ve restarted the vCenter service and so far these alerts have stopped being sent. I have yet to find a root cause for these erroneous alerts or any kb article that fits the problem but it was only occurring with the new IBM HS23E blades with ESXi 5 but not recently built HS22 blades.