Creating the delta resync pair

The delta resync configuration is created after setting up the main TC and UR pairs in the multi-target configuration.

Data is not copied at the time you set up the delta resync pair. The P-VOL and S-VOL in this system contain data from their respective TC and UR systems
If a failure on the primary site occurs, the TC S-VOL is made the primary production volume using the CCI horctakeover command. Differential data stored in the journal volumes is used to synchronize the S-VOL using the resync operation.

Before you begin

A UR delta resync pair can be created in a 3DC multi-target configuration only. To create the multi-target configuration, see 3DC multi-target configuration.
The TC S-VOL is used as the delta resync P-VOL. It must be in PAIR status.
The UR S-VOL is used as the delta resync S-VOL. It must be in PAIR status.
The mirror ID must be between 1 and 3; however, make sure it is not the same as the mirror ID assigned to the UR pair in the 3DC multi-target configuration.
The consistency group you use for the delta resync configuration cannot be used by another UR pair.
Follow volume combinations shown in the section "Volume types that can be shared with Universal Replicator" in the Universal Replicator User Guide.
System option mode 506 must be ON for delta resync.
If you create more than one delta resync pair, the delta resync P-VOLs in the same master journal must use the same mirror ID.

Procedure

Install and set up TC and UR on the required systems.
Create a 3DC multi-target configuration.
1. Crete a TC pair from the primary storage system to the TC secondary site.
2. When the TC pair’s status is PAIR, create the UR pair from the primary storage system to the UR secondary site.
Create a second UR pair from the TC S-VOL to the UR S-VOL. Specify the Initial Copy option as Delta.
When creating UR delta resync pair, select different mirror ID (Mirror ID 1 to 3) than the mirror ID which was used in step 2.