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

• The standard snapshot is not an independent duplicate of the original data. (It is
however possible that in time, every single storage block in the source volume
has been updated and therefore copied.)
• Adequate space is guaranteed for the snapshot, even if all the data in the source
volumes changes.
• It is space-inefficient. Enough space is always reserved for all the data to be
changed, though normally only part is used. While the snapshot exists, the rest
of the reserved space cannot be used for any other purpose.
Impact on application performance
When a backup system accesses the snapshot, it reads disk blocks from both the
source volumes and the replica. Consequently, both the application and the backup
systems disk resources are used, which results in the application performance
degradation when the array is excessively loaded.
Vsnap
With vsnap snapshot, no storage capacity is reserved at the start. Otherwise, the
process is very similar to that for the standard snapshot:
Concepts guide 27