vaai - Delete status "unsupported"

Hi Friends,

I have an interesting issue where one of the VAAI primitive stays "unsupported"

configuration:

VMware ESXi, 5.1.0, 799733

Storage: Hitachi VSP

               FC

               Two luns, 1) 10GB and 2) 1TB

               Both are in same Host-Groups so same Host-mode options are applied to them.

Here is what I see

Only difference is the size - one lun is 10gb which is showing as everything supported while other one is 1TB and Delete Status says "unsupported"

Your input is greatly appreciated.

Thank you,

PK.