When you specify an extended consistency group and split data volume pairs in the specified group collectively, you can specify "Flush" or "Purge" as the suspend mode:
–If you specify "Flush", all pairs in the extended consistency group can be split while consistency of data update sequence will be maintained within that group.
–If you specify "Purge", consistency of data update sequence will not be maintained within the extended consistency group. However, consistency of data update sequence will be maintained within each journal group. Furthermore, the pairs will be split faster than when "Flush" is specified.
If you wish to split, restore or release data volume pairs in an extended consistency group, you can split, restore or release all data volume pairs that belongs to a specific journal group in the extended consistency group collectively. If you collectively split data volume pairs that belong to a specific journal group in the extended consistency group, the supervisor DKC will execute arbitration processing on the other journal groups. For example, in the case described in Figure
3.If you restore data volume pairs in journal group 1, the supervisor DKC will execute arbitration processing on journal groups 1 and 3.
Note: When you collectively split data volumes pairs in a specific journal group in an extended consistency group, you cannot use the REVERSE option of the Business Continuity Manager YKSUSPND command.
Chapter 7 Using Extended Consistency Groups |
