Snapshot data is data in the pool, which is replaced data. Use this workflow to store snapshot data in the pool.
After you create a Thin Image Advanced pair, you can store snapshot data of the pair by splitting the pair. Retaining data of the P-VOL at the time the pair was split in the S-VOL by splitting the pair is referred to as "storing snapshot data". A pair used for storing snapshot data is referred to as a "pair with the snapshot attribute".
The following describes how data in the P-VOL at a certain point in time is retained in the S-VOL when snapshot data is stored.
For Thin Image Advanced, the data of the P-VOL stored in a pool is shared with the S-VOL.
The following figure shows the processing of when the P-VOL data is updated while the pair is split.
If the P-VOL data is updated when the pair has been split, the following processing are performed:
- Information of the stored location (in the pool) is updated for the updated data in the P-VOL.
- The new data (to which deduplication and compression have been applied) is written to the pool.
When the pair has been split, the S-VOL retains data at the point the pair was split.
When the pair has been split, the S-VOL receives write requests from hosts. The following figure shows the processing of when the S-VOL data is updated while the pair is split. If the S-VOL data is updated, the same processing as on the P-VOL is performed on the S-VOL.
Thus, the P-VOL and the S-VOL share the same data at the point the pair was split, and deduplication and compression is applied to the data, which ensures capacity efficient operations. Also, because the P-VOL and the S-VOL receives the same read/write access, you can maintain operations so that the performance load on the P-VOL and the S-VOL is almost the same.