HP XP Continuous Access Software - Manual (Page 164)

10 Disaster recovery operations
Preparing for disaster recovery
The type of disaster and the status of the XP Continuous Access Journal volume pairs determines
the best approach for disaster recovery. Unfortunately, some disasters are not “orderly” and involve
intermittent or gradual failures occurring over a longer time period. You should anticipate and
plan for all types of failures and disasters.
The major steps in preparing for disaster recovery are:
1. Identify journal groups and data volumes containing important files and data for disaster
recovery.
2. For XP Command View Advanced Edition Software, install the management station. For XP
Command View Advanced Edition Software or XP Remote Web Console, install the XP
Continuous Access Journal hardware and software, and establish XP Continuous Access Journal
operations for journal groups and data volumes identified in step 1.
3. Establish file and database recovery procedures. These procedures should already be
established for recovering data volumes that become inaccessible due to some failure.
4. Install and configure host failover software between the primary and secondary sites.
File and database recovery procedures
When the primary or secondary array suspends an XP Continuous Access Journal pair due to a
disaster, the secondary data volume might contain in-process data. A dataset could be open or
transactions might not have completed. Therefore, you must establish file recovery procedures.
These procedures should be the same as those used for recovering data volume that becomes
inaccessible due to a control unit failure.
XP Continuous Access Journal does not provide procedures for detecting and retrieving lost updates.
To detect and recreate lost updates, you must check other current information (for example, database
log files) that was active at the primary site when the disaster occurred. Since this detection/retrieval
process can take a while, your disaster recovery scenario should be designed so that
detection/retrieval of lost updates is performed after the application has started at the secondary
site.
To prepare for file and database recovery, use the files for file recovery (for example, database
log files that have been verified as current).
IMPORTANT: Remote copy and disaster recovery procedures are inherently complex. Consult
your HP account support representative on recovery procedures.
NOTE: See Power management for arrays and network relay devices for information on recovering
a pinned track on an XP Continuous Access Journal volume.
Switching operations to the secondary site
If a disaster or failure occurs at the primary site, the first disaster recovery activity is to switch your
operations to the secondary site. Executing the XP RAID Manager
horctakeover command on
XP Continuous Access Journal pairs enables your business tasks to be taken over to the secondary
site, using secondary data volumes in the secondary site. The
horctakeover command checks
the pair status of secondary data volumes and splits journal groups that will become an XP
Continuous Access Journal pair. This ensures consistency of secondary data volumes and makes
the secondary data volumes usable. If possible, the
horctakeover command attempts to restore
pairs to reverse primary and secondary data volumes. If the horctakeover command executes
successfully, your business tasks will be taken over to (or your business application will be started
164 Disaster recovery operations