HP XP P9500 Storage - Manual (Page 6)

1 Overview of Fast Snap
You can use Fast Snap (FS) to perform cost-effective duplication by storing only differential data
between primary volumes (P-VOLs) and secondary volumes (S-VOLs) of virtual volumes (V-VOLs).
Fast Snap
FS stores snapshots, or a duplicate, of data in your P9500 storage system. Snapshot data is a
copy of updated data in FS P-VOLs.
You can use this data in open-system volumes. If a data storage failure occurs in your storage
system, you can use the snapshot data to restore the data.
The following image shows an overview of FS.
Use the following process to store snapshot data:
1. You create an FS pair.
The P-VOL of an FS pair is a logical volume. The S-VOL of a FS pair is a V-VOL.
2. The host updates the P-VOL.
Updating the P-VOL first copies the updated data as snapshot data in pool volumes (pool-VOL).
This processing is referred to as the storing of snapshot data.
3. You split the FS pair.
The P-VOL snapshot data is stored (this is snapshot A in the figure below).
4. The host updates the P-VOL again.
5. You split the FS pair.
FS stores the updated data in the P-VOL as snapshot data. You can store up to 1,024 snapshots
for a P-VOL. Using FS, you can create up to 1,024 snapshots of data.
The following figure shows how data is stored. The updated data in the P-VOL is Snapshot
data B. The host references the P-VOL, which includes Snapshot data A and Snapshot data
B. Snapshot data A and B are handled as FS S-VOLs.
6 Overview of Fast Snap