Accusys ExaSAN B08S2-PS - Manual (Page 86)

4. How to Use
User Guide Page 4-35
4.1.2.8.5 Snapshot
A snapshot is initialized with a data sync task running in the background to duplicate the data from a
source to a target. The host I/O data is also replicated in the target. The mirror snapshot is offered by the
ExaSAN RAID controller.
Note
The source and target volume of the snapshot must be identical.
Before setting a snapshot, you need to set the slice in the array. The capacity of each slice and the number
of shots should be in accordance with the space you need.
Suppose that an array has the capacity of 30 TB, you may divide it into three slices of 10TB. You must
set the LUN map for the first slice. Setting the LUN map for the other two slices is not required.
Figure 79: Snapshot concept
In the figure above, a snapshot can be created by splitting the source and target after the background sync
is completed. The I/O mirroring is stopped, and the difference is under tracking in a bitmap table to
support fast re-sync.