Volume Manager does not detect Hitachi VSP thin provisioned LUNs as being thin-capable under 5.1 and cannot perform thin reclamation.
Early versions of the Hitachi Array Support Library did not have thin provisioning detection enabled for the VSP type storage array.
Support for thin provisioning on Hitachi VSP arrays was added completely in the VRTSaslapm package version 5.1.001.400. If you have earlier version installed and want Thin Provisioning support, you should update to a minimum 5.1.001.400 or later.
Use the Symantec Operations Readiness Tool website to locate the latest version of the ASL package for the affected platform: