3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

15.3
Reclaiming Space
InForm OS Version 2.2.4 3PAR InForm OS Concepts Guide
15.2.1 Reclaiming Volume Space
When multiple identical virtual volumes are created as a result of a single volume creation
operation, the underlying logical disks that support those volumes are shared by the volume
group. If several of the members of that volume group are later deleted, the underlying logical
disks may become less efficient in terms of space. One or more logical disks shared by the
volume group may have only a small portion of their regions mapped to existing virtual
volumes. However, their unused regions are not available to the system for use in creating new
logical disks. Compacting the logical disk regions mapped to these volumes may recover and
free a certain amount of logical disk space.
15.2.2 Reclaiming CPG Space
Common Provisioning Groups (CPGs) provide a shared logical capacity pool for use by all
virtual volumes that draw space from that pool (see Virtual Volume Types and Variations on
page 8.5 for a discussion of volumes that can draw space from a CPG). If volumes that draw
from a CPG are deleted, or if copy space for these volumes grows and then shrinks, the
underlying logical disks in the CPG pool can become less efficient in terms of space. One or
more logical disks in the CPG pool may have only a small portion of their regions mapped to
existing virtual volumes. However, their unused regions are not available for use by the
volumes mapped to the CPG. Compacting the logical disk regions mapped to these volumes
may recover and free a certain amount of logical disk space. Compacting CPG space is achieved
using the
compactcpg command. For detailed instructions on compacting logical disk space,
see the InForm OS CLI Administrator’s Manual.