I have an ESXi 5.1 host that uses two NICs bounds to an iSCSI software initiator to connect to two separate storage arrays: array A and array B. Every few hours, I will see this series of events in the ESXi logs:
1) path redundancy to storage device naa.[whatever] degraded. Path vmhba39:C11:T0:L1 is down. Affected datastores: <datastore_name>
2) alarm 'cannot connect to storage' from gray to gray
3) path redundancy to storage device naa.[whatever] (Datastores: <datastore_name>) restored. Path vmhba39:C11:T0:L1 is active again. (this event occurs about 30 seconds after event #1)
This ESXi host never loses contact with both array A and array B at the same time. But over time I do see these alerts involving array A and array B. The few test VMs I have running on this host appear to stay up and running without issue.
I have thought from the beginning this may be a hardware issue, so I switched out the cables and moved both my iSCSI connections to the same physical switch as one of array A. I still see these events with array A though. Would appreciate any thoughts on what to try next. Thanks in advance.