Managing Virtual Volume Copies; Virtual Copies; Creating A Virtual Copy - HP 3PAR StoreServ 7200 2-node Administrator's Manual

7 Managing Virtual Volume Copies

There are two types of copies that can be created from virtual volumes: virtual copies and physical
copies.
A virtual copy is a snapshot of an original or base volume. A virtual copy only records the
changes to the original virtual volume.
A physical copy is a complete duplicate of all the data from a base volume to a destination
volume.
For more information about virtual copies, see the HP 3PAR StoreServ Storage Concepts Guide.
NOTE: Creating TPVVs requires the HP 3PAR Thin Provisioning Software license. Creating virtual
copies or snapshots requires the HP 3PAR Virtual Copy Software license.
NOTE:
If your system is accessible in an OpenStack cloud, you may see volumes with prefixes indicating
that the volumes were created through the OpenStack cloud. Volumes created through the OpenStack
cloud use the OpenStack Volume (OSV) and OpenStack Snapshot (OSS) prefixes.

Virtual Copies

A virtual copy is a snapshot of another virtual volume. You can make virtual copies of base volumes,
physical copies, or other virtual copies. Virtual copies are created using copy-on-write techniques
available only with the HP 3PAR Virtual Copy Software license. Unlike a physical copy which
duplicates the entire base volume, a virtual copy only records the changes to the original volume.
This allows an earlier state of the original volume to be recreated by starting with the current state
and rolling back all of the changes that have been made since the virtual copy was created.
You can use the HP 3PAR CLI to perform the following virtual copy tasks:
Create
Promote
Modify
Remove
For additional information about virtual copies, see the HP 3PAR StoreServ Storage Concepts
Guide.

Creating a Virtual Copy

Virtual copies can be read-only or read/write. Read-only and read/write copies must alternate.
You can only make a read-only copy of a read/write volume and a read/write copy of a read-only
volume. Expiration dates can be set for virtual copies to save space. The system allows you to
make a maximum of 500 virtual copies of a base volume. Up to 256 virtual copies can be
read/write copies.
The maximum number of virtual copies that can be created on a system is determined by the system
configuration. For the maximum number of virtual copies that can be created with your specific
system configuration, see the SPOCK website:
http://www.hp.com/storage/spock
To create a virtual copy, or snapshot, of a virtual volume or a virtual volume set, issue the createsv
-ro <snapshot_name> <source_VV>|set:<set_name> command, where:
-ro specifies that the snapshot being created is read-only.
<snapshot_name> is the name of the snapshot being created.
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