Friday, July 13, 2012

ESXi 4.x / 5.x lun bigger than 2tb grayed out

Issue: A 4tb lun which was working fine with a VM running in it, is grayed out. The Virtual Machine(s) is/are working fine in it but the lun itself seems to be not responding.

Cause: The cluster has both esxi 4.x and 5.x hosts and 4.x hosts cannot handle or see luns larger than 2tb-512kb where as 5.x hosts can handle luns of the size of upto 64tb. This causes a conflict of interest among the hosts for the lun > 2tb and thus it becomes grayed out.

Resolution :  Luckily the VM which was running in that lun was running on 5.x host and if it was running in 4.x host then the first thing to do is to vmotion the vm to a host of 4.x; then unpresent the lun from the storage to all the 4.x host and do a rescan for datastores for the cluster (right click on the cluster>scan for datastores).