HP 3PAR InForm OS 3.1.1 Concepts Guide

Zeroing Unused Space
Use a host application to write zeros to the allocated but unused volume space. F-Class, T-Class,
and P10000 Storage Systems detect and discard the zeros during the volume copy operation.
Creating a Physical Copy
After writing zeros to the allocated but unused space, the source volume is ready for the final phase
of conversion. You create a TPVV physical copy of the source volume to convert the source volume
to a TPVV. When you create a physical copy, F-Class, T-Class, and P10000 Storage Systems
automatically detect the zeros and do not allocate space for them in the physical copy. The result
is a TPVV that is much smaller than the original volume.
Thin Conversion tasks can be performed with both the HP 3PAR OS Command Line Interface (CLI)
and the HP 3PAR Management Console. Refer to the HP 3PAR OS CLI Administrator’s Manual
and the HP 3PAR Management Console Online Help for instructions on how to perform these tasks.
NOTE: Converting fully-provisioned volumes to Thinly-Provisioned Virtual Volumes (TPVVs) with
the Thin Conversion feature requires an F-Class, T-Class, or P10000 Storage System, an HP 3PAR
Thin Provisioning license, and an HP 3PAR Thin Conversion license. Contact your HP representative
for more information.
HP 3PAR Thin Persistence Software
HP 3PAR Thin Persistence Software is an optional feature that keeps TPVVs and read/write snapshots
of TPVVs small by detecting pages of zeros during data transfers and not allocating space for the
zeros. This feature works in real-time and analyzes the data before it is written to the source TPVV
or read/write snapshot of the TPVV. Freed blocks of 16 KB of contiguous space are returned to
the source volume, freed blocks of 128 MB of contiguous space are returned to the CPG for use
by other volumes.
To use Thin Persistence functions, you must have an F-Class, T-Class, or P10000 Storage System.
The Thin Persistence feature is automatically enabled on F-Class, T-Class, and P10000 Storage
Systems. Thin Persistence tasks can be performed with both the HP 3PAR OS Command Line
Interface (CLI) and the HP 3PAR Management Console. Refer to the HP 3PAR OS CLI Administrator’s
Manual and the HP 3PAR Management Console Online Help for instructions on how to perform
these tasks.
NOTE: Maintaining TPVV and read/write snapshot size with the Thin Persistence feature requires
an F-Class, T-Class, or P10000 Storage System, an HP 3PAR Thin Provisioning license, an HP
3PAR Thin Conversion license, and an HP 3PAR Thin Persistence license. Contact your HP
representative for more information.
Thin Copy Reclamation Software
Thin Copy Reclamation Software is an optional feature that reclaims space when snapshots are
deleted from a system. As snapshots are deleted, the snapshot space is reclaimed from a
Thinly-Provisioned Virtual Volume (TPVV) or fully-provisioned virtual volume and returned to the
CPG for reuse by other volumes. Deleted snapshot space can be reclaimed from virtual copies,
physical copies, or remote copies. The Thin Copy Reclamation feature works on any class of system.
The HP 3PAR OS automatically reclaims snapshot space if the Virtual Copy, Remote Copy, or Thin
Provisioning license is enabled. For more information about snapshots, see “Virtual Copy Snapshots”
(page 15).
NOTE: Reclaiming space when snapshots are deleted with the Thin Copy Reclamation feature
requires the Virtual Copy, Remote Copy, or Thin Provisioning license. Contact your HP representative
for more information.
56 Enhanced Storage Applications