Hi,
it's the Path, through which HBA access the LUN, is dead. Please try following steps:
1. Check the LUN status in Storage array Management Software, also check if the SP's( Storage Processors/Controllers) are fine
2. If in above steps everything is fine at storage array, check Fabric Switches could be an issue with them(check zoning information on them as well)
3. If everything is fine in above 2 steps, try to unpresent and represent the LUN using following procedure:
a: Unpresent the lun using Storage Array Management software, on ESX host rescan the HBAs
b: after rescan HBAs represent the LUN's and rescan again.
Hope that above steps resolve the issue.
Regards
