Chapter 10 Usage Scenarios 10-7
Hitachi Universal Replicator for IBM /OS User’s Guide
6. If there is no secondary data volume (which is originally a primary data
volume) whose pair status is other than Suspend (equivalent to SUSPOP
with Business Continuity Manager), data in primary data volumes are the
same as data in secondary data volumes, and the secondary data volume
(which are originally primary data volumes) are usable. Please resume
applications at the primary site.
7. Execute the YKSUSPND REVERSE command on the restore journal group
(which were originally master journal group); YKSUSPND is a Business
Continuity Manager command and REVERSE is an option. Wait until
suspension completes.
8. After suspension completes, execute the Business Continuity Manager
YKRESYNC REVERSE command on the restore journal group (which were
originally master journal group). This reverses primary data volumes and
secondary data volumes to resynchronize pairs and restores copy direction
to its original direction..
For detailed information about how to use Business Continuity Manager, please
refer to Business Continuity Manager User's Guide.
For detailed information about status of data volumes, refer to section
Pair
Status.
Disaster Recovery for Multiple Primary and Secondary Storage
Systems
Consistency of Data Update Sequence When a Disaster Occurs
When a failure occurs in some primary or secondary storage system, all
journal groups in the extended consistency group will be suspended and
remote copy operations will be suspended. The consistency of data update
sequence will be maintained if a failure occurs in a primary storage system,
but the consistency will not be maintained if a failure occurs in a secondary
storage system.
For example, in the case described in
Figure 10-1, if a failure occurs in the
primary storage system 1 at 10:00 a.m., journal groups 1 to 3 will be
suspended due to the failure, and the data written from the host before 10:00
a.m. will be restored to secondary data volumes in the secondary EXCTG,
while consistency of data update sequence is maintained. On the other hand, if
a failure occurs in the secondary storage system 1, journal groups 1 to 3 will
be suspended due to the failure, and the consistency of the data update
sequence will not be maintained for secondary data volumes in the extended
consistency group.
