HP Application Recovery Manager software A.06.10 Concepts guide (March 2008)

Figure 4 Split mirror replication
When a mirror is first created, data in it is synchronized until it is identical to that in
the source volumes. During normal application usage, the mirror volumes are kept
synchronized with the source volumes. Any updates to the source volumes are also
applied to the mirror volumes.
When a replica of the data at a fixed point in time is required for an administrative
task (such as backup):
1. Synchronization between the mirrored volumes is stopped (the mirror is split)
leaving an independent replica of the source volumes.
2. The replica is used for the backup or other task, leaving the application to
continue virtually unaffected using the source data.
3. If necessary, after the work on the replica is complete, the two sets of data can
be resynchronized until mirrored data is required for another administrative task.
Splitting is very fast and has minimal impact on the application system.
Characteristics of split mirror replicas
• A split mirror replica is a complete duplicate (or clone) of the source volumes,
which, from the point of view of the host/operating system, is identical to the
source at the moment the duplicate was created.
At the physical disk or logical unit level, a complete physical copy of contents of
the source storage blocks exists.
• It is completely independent of the original.
Replication techniques24