Dell EMC PowerVault MD 34XX/38XX Series Storage Arrays Administrator's Guide

In version 8.25, the Thin Provisioning feature is enhanced to support the UNMAP command, through the command-line interface. Any thinly provisioned virtual disks that are configured on a storage array before an upgrade to version 8.25 are still available after the upgrade and supports the UNMAP command. However, in previous versions of the MD Storage Manager operating system, thinly provisioned virtual disks are reported to the host operating systems as standard virtual disks.

Existing thinly provisioned virtual disks in a storage array that you upgrade to version 8.25 are still reported to the host operating system as standard virtual disks until, you use the command-line interface to set the reporting status to thin. Thinly provisioned virtual disks that you configure after upgrading to version 8.25 are reported to the host operating systems as thinly provisioned virtual disks.