HP MSA2324sa HP StorageWorks 2000 G2 Modular Smart Array reference guide (5009 - Page 22
The destination vdisk must have free space that is at least as large as the mount of space allocated
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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 Data transfer New volume 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 Snapshot(s) Data transfer New 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 Guidelines to keep in mind when performing a volume copy include: • The destination vdisk must be owned by the same controller as the source volume. • The destination vdisk must have free space that is at least as large as the mount of space allocated to the original volume. A new volume will be created using this free space for the volume copy. • The destination vdisk does not need to have the same attributes (such as disk type, RAID level) as the volume being copied. • Once the copy is complete, the new volume will no longer have any ties to the original. • Volume Copy makes a copy from a snapshot of the source volume; therefore, the snap pool for the source volume must have sufficient space to store snapshot data when performing this copy. 22 Getting started