Functions That Support Disaster Recovery; The Reverse Resync Function - HP XP P9500 Software User's Manual

Figure 41 APID concept

Functions That Support Disaster Recovery

This section describes the Business Continuity Manager functions that support disaster recovery
(such as the Reverse Resync function and Continuous Access Synchronous consistency preservation
function).

The Reverse Resync Function

The Reverse Resync function is used to reverse the direction of copy operations (reverse the roles
of the P-VOL and S-VOL). Because the Reverse Resync function only copies the differences between
a P-VOL and an S-VOL, it shortens the time required for recovering the operation.
Implement the Reverse Resync function by using the YKSUSPND and YKRESYNC commands, in
combination.
The following procedure describes the flow of failovers and failbacks using the Reverse Resync
function. The numbers in the following steps correspond to the numbers in
1. Stop all applications at the primary site.
2. Reverse the copy direction by using the Reverse Resync function.
To reverse the copy direction, execute the YKSUSPND and YKRESYNC commands with the
REVERSE parameter specified for both.
3. Start all applications at the secondary site.
Perform a maintenance and failure recovery at the primary site while operations are being
performed at the secondary site.
Figure 42 (page
Functions That Support Disaster Recovery
78).
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