3DC multi-target configuration using delta resync with three UR sites

You create a UR pair that connects the two secondary sites so that the remote copy system can be created immediately using the two secondary sites if a failure or disaster occurs at the primary site. A UR pair that is created to make a triangle-shaped remote copy connection among the three sites is called UR delta resync pair. By creating a UR delta resync pair between the two secondary sites in advance, you can transfer the copying operations from between the two secondary sites back to between the primary and secondary sites in a short time when the primary site failure is corrected and the primary site is brought back online.

The following illustration shows the 3DC multi-target configuration using delta resync with three UR sites.

 For a 3DC multi-target configuration using delta resync with three UR sites, both the P-VOL and S-VOL of a UR delta resync pair are displayed as secondary volumes in the Remote Replication window (Pair Position column).