Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Physical Data Replication for ContinentalClusters Using Continuous Access XP
Maintaining the Continuous Access XP Data Replication Environment
Chapter 6322
This command must successfully complete for disaster-tolerant data
protection to be restored. Following is a partial list of failures that
require running pairresync to restore disaster-tolerant data protection:
• failure of ALL CA links without restart of the application
• failure of ALL CA links with Fence Level DATA with restart of the
application on a primary host
• failure of the entire recovery Data Center for a given application
package
• failure of the recovery XP disk array for a given application package
while the application is running on a primary host
Following is a partial list of failures that require full resynchronization
to restore disaster-tolerant data protection. Full resynchronization is
automatically initiated by moving the application package back to its
primary host after repairing the failure.
• failure of the entire primary Data Center for a given application
package
• failure of all of the primary hosts for a given application package
• failure of the primary XP disk array for a given application package
• failure of all CA links with application restart on a secondary host
NOTE The preceding steps are automated provided the default value of 1 is
being used for the auto variable AUTO_PSUEPSUS. Once the CA link
failure has been fixed, the user only needs to halt the package at the
failover site and restart on the primary site. However, if you want to
reduce the amount of application downtime, you should manually invoke
pairresync before failback.
Full resynchronization must be manually initiated as described in the
next section) after repairing the following failures:
• failure of the recovery XP disk array for a given application package
followed by application startup on a primary host
• failure of all CA links with Fence Level NEVER or ASYNC with restart
of the application on a primary host