esx.problem.vmfs.error.volume.is.locked
Summary
Host made an attempt to access a VMFS datastore that is locked by another host.
Causes
I/O error, perhaps caused by bad shutdown due to power failure, or faulty controller/connection.
Resolutions
You may attempt to reload the VMFS volume metadata with the following command:
# vmkfstools -B <vmfs device>
Refer to this VMware KB article for more information.
External
Refer to the VMware Online Documentation for more information on vCenter event messages and possible solutions.