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Figure 12-1
Copy-on-Write Technology
Snapshot Rollback
Rollback restores the data back to the state of any time which was previously captured in
case for any unfortunate reason it might be. Snapshot volume is allocated within the same
pool in which the snapshot is taken, we suggest reserving 20% of the pool capacity or more
for snapshot space.
Writable Snapshot
Apart from the rollback function, snapshot allows direct access to the snapshot content
with read or read/write permissions. There are two benefits: One is that it will not consume
the free capacity of the storage pool. The other one is that it will not affect the content of
the target volume. Before attaching a LUN to the snapshot, the snapshot needs to be
exposed to be prepared for accessing. An example of these benefits would be,
programmers or developers can easily test a previous version of their compiled codes
simply by mounting an older snapshot version onto a LUN instead of rolling back the
snapshot and overwriting the existing source codes.