If your ESXi host is unable to access a LUN, or access is very slow, you might have a problem with path thrashing, also called LUN thrashing.

Your host is unable to access a LUN, or access is very slow. The host's log files might indicate frequent path state changes. For example:

Frequent path state changes are occurring for path vmhba2:C0:T0:L3. This may indicate a storage problem. Affected device: naa.600600000000000000edd1. Affected datastores: ds1

The problem might be caused by path thrashing. Path thrashing might occur when two hosts access the same LUN through different storage processors (SPs) and, as a result, the LUN is never available.

Path thrashing typically occurs on active-passive arrays. Path thrashing can also occur on a directly connected array with HBA failover on one or more nodes. Active-active arrays or arrays that provide transparent failover do not cause path thrashing.

1

Ensure that all hosts that share the same set of LUNs on the active-passive arrays use the same storage processor.

2

Correct any cabling or masking inconsistencies between different hosts and SAN targets so that all HBAs see the same targets.

3

Ensure that the claim rules defined on all hosts that share the LUNs are exactly the same.

4

Configure the path to use the Most Recently Used PSP, which is the default.