Hitachi Universal Replicator for z/OS User Guide: HP XP12000 Disk Array, HP XP10000 Disk Array, HP 200 Storage Virtualization System (T1778-96021, May 2011)

Figure 7 Delta Resync Setting in 3DC Multi-target Configuration (After Failure Occurred)
In Figure 7 (page 28), because a failure occurs in the primary site A, Business Continuity Manager
is used to change the former TCz Synchronous secondary site to the primary site B. If you perform
delta resync operation in this situation, the URz pair for delta resync operation in “Delta Resync
Setting in 3DC Multi-target Configuration (Before Failure Occurs)” (page 26) will be synchronized
and usable.
When you perform delta resync operation, first the journal data in the primary site B are copied
to the URz secondary site by journal copy. In this journal copy, only the journal data which is not
yet restored to the secondary data volume in the URz secondary site are copied in chronological
order. When the journal copy completes, journal restore takes place in the URz secondary site.
28 Overview of Universal Replicator for Mainframe Operations