Hitachi MP-96RD625-01 manual Primary host Primary Exctg

You can remove journal groups from an extended consistency group anytime, regardless of the status of the journal groups. Also, if you delete all data volumes from a journal group in an extended consistency group, the journal group will automatically be removed from the extended consistency group.

Removal of journal groups from an extended consistency group does not stop remote copy operations, but does affect consistency in data update sequence. In the example in Figure 7-2 below, if you remove the journal group 1 from the secondary EXCTG, the remote copy operation from the primary storage system 1 to the secondary storage system 1 will continue. However, consistency in data update sequence will only be maintained among the primary storage systems 2 and 3 and the secondary storage systems 2 and 3.

Write data

Primary host
Primary EXCTG	Secondary EXCTG
Journal group 1	Journal group 1
Primary data	Secondary data
volume	volume
Master JNL VOL	Restore JNL VOL
Primary subsystem 1	Secondary subsystem 1
Journal group 2	Journal group 2
Primary data	Secondary data
volume	volume
Master JNL VOL	Restore JNL VOL
Primary subsystem 2	Secondary subsystem 2
Journal group 3	Journal group 3
Primary data	Secondary data
volume	volume
Master JNL VOL	Restore JNL VOL
Primary subsystem 3	Secondary subsystem 3

Figure 7-2 Example 1: Remote Copy Operations Among Three Primary Storage Systems and Three Secondary Storage Systems

7-8 Chapter 7 Using Extended Consistency Groups

Hitachi Universal Replicator for IBM /OS User’s Guide