Last night I was working through a couple of the storage objectives for the VCAP5-DCA. One of the required skills of blueprint Objective 1.1, Implement and Manage Complex Storage Soltuions, is to understand and apply LUN masking. Jason Langer did an excellent write up on Using esxcli to Mask a LUN from ESXi on his site so I won’t repeat the whole process here but I did run into an interesting issue.
If LUN is being used as a Heartbeat Datastore by HA an error will be produced when trying to unclaim the last path to the LUN.
~ # esxcli storage core claiming unclaim -t location -A vmhba33 -C 1 -T 0 -L 8
Unable to perform unclaim. Error message was : Sysinfo error on operation returned status : Busy. Please see the VMkernel log for detailed error information
The Heartbeat Datastore preferences have to be changed so that the LUN is no longer used by HA before you will be able to mask the LUN from the host.