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

8.6
Virtual Volume Types and Variations
3PAR InForm OS Concepts Guide InForm OS Version 2.2.4
The snapshot data and snapshot administration spaces for a given base volume are used for all
the virtual copies created from that parent volume (when applicable). If either of these spaces
becomes full, a copy-on-write operation fails.
The size of these spaces is fixed when the base volume is created, but can be changed later by
growing, or increasing the size of, the volume.
For additional information, see the InForm OS CLI Administrator’s Manual and the InForm OS
Management Console Online Help.
8.7.2 Physical Copies
A physical copy is a snapshot-in-time that duplicates all the data from one base volume to
another base volume (the destination volume). This is done so that the data on the destination
volume can be used if the original volume becomes unavailable. Any changes to either volume
will cause them to lose sync with each other, which can be remedied by resynchronizing the
two volumes as described in the InForm OS CLI Administrator’s Manual and the InForm OS
Management Console Online Help.
A physical copy can only be made from a base volume with enough free snapshot data space to
accommodate writes to that volume during the physical copy operation. In addition, the
destination volume must meet the following conditions:
■ It must also be a base volume.
■ It must have at least as much user space as that of the volume being copied.
■ It must not be exported.
Refer to the InForm OS CLI Administrator’s Manual or the InForm OS Management Console
Online Help for instructions on creating physical copies.
NOTE: To halt volume export, you must delete all VLUNs associated with the
volume. After doing so, you can use the volume as a destination volume for a
physical copy operation.
NOTE: If the parent and destination volume are both thinly provisioned virtual
volumes (TPVVs), only the actual used space is copied. See Chapter 2, Overview for
additional information on TPVVs.