HP StorageWorks XP Remote Web Console Software - Manual (Page 63)

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 20 (page 63) , 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.
Figure 20 Example 2: Remote Copy Operations Among Three Primary Storage Systems and Three
Secondary Storage Systems
Disaster Recovery Procedure
The following is an example of the procedure that should be followed when a disaster or failure
occurs in the primary site in multi-primary and multi-secondary storage systems configuration:
1. Switch operations from the primary site to the secondary site.
2. Reverse the copy direction, so that data are copied from the secondary site to the primary
site.
3. After recovery of the primary host or storage system finishes, switch operations from the
secondary site to the primary site.
This disaster recovery procedure is the same as when only one primary storage system and only
one secondary storage system is used.
Using More Than One Primary and Secondary Storage System for Remote Console 63