Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

You can only perform Thin Reclamation on thin_rclm LUNs. VxVM automatically
discovers LUNs that support Thin Reclamation from capable storage arrays. To
list devices that are known to be thin or thin_rclm on a host, use the vxdisk -o
thin list command.
You can only perform Thin Reclamation if the disks support a mounted VxFS file
system.
For more information on how to trigger Thin Reclamation on a VxFS file system,
see the Veritas File System Administrator's Guide.
Thin Reclamation takes considerable amount of time when you reclaim thin
storage on a large number of LUNs or an enclosure or disk group.
349Administering volumes
Using Thin Provisioning