LUN is not in ready state at Storage System Level and caused Datastore not responding issue and data store I/O read error

Issue:  Host Triggered "cannot connect to the Storage Alarm"

Findings:  found below error logs on ESXi Kernel logs



D:0x2 P:0x0 Valid sense data: 0x2 0x4 0x3.
2015-03-26T14:56:37.630Z cpu27:49007)Partition: 423: Failed read for "naa.60000900000000005533030423042": I/O error
2015-03-26T14:56:37.630Z cpu27:49007)Partition: 1003: Failed to read protective mbr on "naa.60000900000000005533030423042" : I/O error
2015-03-26T14:56:37.630Z cpu27:49007)WARNING: Partition: 1112: Partition table read from device naa.60000900000000005533030423042 failed: I/O error
/ # 2015-03-26T14:56:37.664Z cpu30:33690)ScsiDeviceIO: 2338: Cmd(0x4136829cd900) 0x28, CmdSN 0x14 from world 49007 to dev "naa.60000900000000005533030423042" failed H:0x0 D:0x2 P:0x0 Valid sense data: 0x2 0x4 0x3.
2015-03-26T14:56:37.666Z cpu30:33690)ScsiDeviceIO: 2338: Cmd(0x4136829d3500) 0x88, CmdSN 0x15 from world 49007 to dev "naa.60000900000000005533030423042" failed H:0x0 D:0x2




The D:0x2 scsi messages are indicative of a 'LOGICAL UNIT NOT READY'

reference KB article

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1030381


http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=289902

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1010244


Solution: 

Escalated the issue to Storage team and Storage team to found out that this particular LUN was changed from ready state to offline ( not ready state). and they brought up the LUN to ready state. now the Data store is back to normal and running fine.