Dell PowerVault ME5 Series Administrator's Guide

Copying volumes or snapshots

The volume copy feature (Provisioning > Volumes > volume slide-over > Copy Volume) enables you to copy a base volume or snapshot to a new volume. It creates a complete "physical" copy of a base volume or snapshot within a storage system. The copy is an exact duplicate of the source as it existed at the time the copy operation was initiated, consumes the same amount of space as the source, and is independent from an I/O perspective. In contrast, the snapshot feature creates a point-in-time "logical" copy of a volume, which remains dependent on the source volume.

The volume copy feature provides the following benefits:

• Additional data protection: An independent copy of a volume provides additional data protection against a complete source volume failure. If the source volume fails, the copy can be used to restore the volume to the point in time when the copy was created.
• Non-disruptive use of production data: With a mounted 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 snapshots) 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 copy operation is performed directly from the source. This source data may change if modified data is to be included in the copy and there are snapshots attached and in use. You must detach the volume before copying it. It is highly recommended to unmount it on the host first, so that the host can flush its cache, before detaching it. The volume will not be available for read or write access until the copy is complete, at which time you can reattach the volume.