3DC multi-target configuration with three UR sites

With Universal Replicator, you can set up two secondary sites for one primary site. It is advisable that you create a UR pair that connects the two secondary sites so that the remote copy system created with the host operation site and backup site can be created immediately in the event of a failure or disaster at the primary site. A UR pair that is created to make a triangle-shaped remote copy connection among the three sites is called a UR delta resync pair. By creating a UR delta resync pair in advance, you can transfer the copying operations from between the secondary sites back to from the primary to the secondary site in a short time when the failure is corrected and the primary site is brought back online.

The following illustration shows the 3DC multi-target configuration with three UR sites:

• UR primary site

• UR secondary site (copies data with a mirror whose ID is an arbitrary number (M in the illustration) from the primary site). Data can be copied with a mirror whose ID is an arbitrary number (P in the illustration) from another secondary site.

• UR secondary site (copies data with a mirror whose ID is an arbitrary number (N in the illustration) from the primary site). Data can be copied with a mirror whose ID is an arbitrary number (P in the illustration) from another secondary site.

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