Chapter 10. Copy services 513
Use case
The user wants to produce a copy of a volume without affecting the availability of the volume.
The user does not anticipate many changes to be made to the source or target volume; a
significant proportion of the volumes remains unchanged.
By ensuring that only changes require a copy of data to be made, the total amount of disk
space that is required for the copy is reduced. Therefore, many Snapshot copies can be used
in the environment.
Snapshots are useful for providing protection against corruption or similar issues with the
validity of the data, but they do not provide protection from physical controller failures.
Snapshots can also provide a vehicle for performing repeatable testing (including “what-if”
modeling that is based on production data) without requiring a full copy of the data to be
provisioned.
Clone
The clone preset creates a replica of the volume, which can be changed without affecting the
original volume. After the copy completes, the mapping that was created by the preset is
automatically deleted.
Clone uses the following preset parameters:
Background copy rate: 50
Incremental: No
Delete after completion: Yes
Cleaning rate: 50
Primary copy source pool: Target pool
Use case
Users want a copy of the volume that they can modify without affecting the original volume.
After the clone is established, there is no expectation that it is refreshed or that there is any
further need to reference the original production data again. If the source is thin-provisioned,
the target is thin-provisioned for the auto-create target.
Backup
The backup preset creates a point-in-time replica of the production data. After the copy
completes, the backup view can be refreshed from the production data, with minimal copying
of data from the production volume to the backup volume.
Backup uses the following preset parameters:
Background Copy rate: 50
Incremental: Yes
Delete after completion: No
Cleaning rate: 50
Primary copy source pool: Target pool
Use case
The user wants to create a copy of the volume that can be used as a backup if the source
becomes unavailable, as in the case of loss of the underlying physical controller. The user
plans to periodically update the secondary copy, and does not want to suffer from the
resource demands of creating a new copy each time (and incremental FlashCopy times are
faster than full copy, which helps to reduce the window where the new backup is not yet fully
effective). If the source is thin-provisioned, the target is also thin-provisioned in this option for
the auto-create target.
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