How data is copied after splitting pair

When you store snapshot data, the Thin Image Advanced pair is split. The following describes the behavior of the storage system when data of the P-VOL and S-VOL of the split pair is updated.

In Thin Image Advanced, the storage system that received a request for updating data in the P-VOL and S-VOL writes the new data to the pool with the Redirect-on-Write (RoW) method.

1. The storage system receives a request for updating data of the P-VOL or S-VOL from a host.
2. The storage system returns to the host the status indicating that the write processing is complete.
3. The new data is written to the pool in the following order:
   1. Deduplication and compression is applied to the new data.
   2. The location management information (metadata) is updated for the updated data.
   3. The new data to which deduplication and compression is applied is written to the pool.

   The new data is written to a different pool area from the pool area that stores data at the point the pair was split (old data). Therefore, the old data is not overwritten.