Reducing the time to vary on independent disk pools

When unplanned outages occur, the data stored within independent disk pools is unavailable until they can be restarted. To ensure that the restart occurs quickly and efficiently, you can use the strategies described in this topic.

Synchronizing user profile name, UID, and GID

In a high-availability environment, a user profile is considered to be the same across systems if the profile names are the same. The name is the unique identifier in the cluster. However, a user profile also contains a user identification number (UID) and group identification number (GID). To reduce the amount of internal processing that occurs during a switchover, where the independent disk pool is made unavailable on one system and then made available on a different system, the UID and GID values should be synchronized across the recovery domain for the device CRG. Administrative Domain can be used to synchronize user profiles, including the UID and GID values, across the cluster.

Using recommended structure for independent disk pools

The system disk pool and basic user disk pools (SYSBAS) should contain primarily operating system objects, licensed program libraries, and few user libraries. This structure yields the best possible protection and performance. Application data is isolated from unrelated faults and can also be processed independently of other system activity. Vary on and switchover times are optimized with this structure.

This recommended structure does not exclude other configurations. For example, you might start by migrating only a small portion of your data to a disk pool group and keeping the bulk of your data in SYSBAS. This is certainly supported. However, you should expect longer vary-on and switchover times with this configuration since additional processing is required to merge database cross-reference information into the disk pool group.

Specifying a recovery time for the independent disk pool

To improve vary on performance after an abnormal vary off, consider specifying a private customized access path recovery time specifically for that independent disk pool by using the Change Recovery for Access Paths (CHGRCYAP) command rather than relying upon the overall system-wide access path recovery time. This will limit the amount of time spent rebuilding access paths during the vary on.