About The Volume Copy Feature - HP P2000 G3 Reference Manual

About the Volume Copy feature

Volume Copy enables you to copy a volume or a snapshot to a new standard volume.
While a snapshot is a point-in-time logical copy of a volume, the volume copy service creates a complete
"physical" copy of a volume within a storage system. It is an exact copy of a source volume as it existed at
the time the volume copy operation was initiated, consumes the same amount of space as the source
volume, and is independent from an I/O perspective. Volume independence is a key distinction of a
volume copy (versus a snapshot, which is a "virtual" copy and dependent on the source volume).
Benefits include:
• Additional data protection. An independent copy of a volume (versus logical copy through snapshot)
provides additional data protection against a complete master volume failure. If the source master
volume fails, the volume copy can be used to restore the volume to the point in time the volume copy
was taken.
• Non-disruptive use of production data. With an independent copy of the volume, resource contention
and the potential performance impact on production volumes is mitigated. Data blocks between the
source and the copied volumes are independent (versus shared with snapshot) so that I/O is to each
set of blocks respectively; application I/O transactions are not competing with each other when
accessing the same data blocks.
The following figure illustrates how volume copies are created.
Creating a volume copy from a standard or master volume
Source volume Transient snapshot
1. Volume copy request is made with a standard volume or a master volume as the source.
2. If the source a standard volume, it is converted to a master volume and a snap pool is created.
3. A new volume is created for the volume copy, and a hidden, transient snapshot is created.
4. Data is transferred from the transient snapshot to the new volume.
5. On completion, the transient volume is deleted and the new volume is a completely independent copy of
the master volume, representing the data that was present when the volume copy was started.
Creating a volume copy from a snapshot
Master volume
1. A master volume exists with one or more snapshots associated with it. Snapshots can be in their original
state or they can be modified.
2. You can select any snapshot to copy, and you can specify that the modified or unmodified data be copied.
3. On completion, the new volume is a completely independent copy of the snapshot. The snapshot remains,
though you can choose to delete it.
Figure 3 Creating a volume copy from a master volume or a snapshot
Data transfer
Snapshot(s) Data transfer
HP StorageWorks P2000 G3 MSA System SMU Reference Guide
New volume
New volume
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