Hitachi Universal Replicator for z/OS user guide for XP12000/XP10000 Disk Arrays and SVS 200 (T1778-96007, October 2007)

TCz Synchronous, UR primary site A URz secondary site
Journal data flow
secondary
subsystem
secondary
dataVOL
restore
JNL VOL
j
ournal restore
primary subsystem
(former secondary subsystem)
primary data VOL
(former R-VOL)
master
JNL VOL
primary
subsystem
Failure
JNL VOL
j
ournal cop
y
URz pair for delta resync operation
Data flow
Write
TCz Synchronous
primary site B
(former secondary site)
master
journal obtain
M-VOL
primary data VOL
primary host secondary host
primary host
(former
secondary host)
Figure 8 Delta Resync Setting in 3DC Multi-target Configuration (After Failure Occurred)
In Figure 8 on page 44, 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 Figure 7 on page 42 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.
44
Overview of Universal Replicator Operations