IRLM and protecting data

The internal resource lock manager (IRLM) can protect your data if an IMS subsystem fails.

If the IRLM is present and remains running, it retains locks on incomplete changes at the database record level after an IMS subsystem fails. The IRLM removes these locks when dynamic backout completes.

If the IRLM fails while its IMS subsystems continue to run, the subsystems stop all work in progress, dynamically back out all incomplete database changes, and call DBRC to relinquish their authorizations to shared databases. After you restart the IRLM, the subsystems resume processing.

If two or more IRLMs are active during block-level data sharing, and one IRLM fails with or without the z/OS® system that it runs under, the surviving IRLMs and their IMS subsystems reauthorize with DBRC the use of all shared databases.

In this case, because the surviving IRLMs know about the block-level locks (that protect the incomplete changes made by the failed subsystem), they permit their IMS subsystems to continue block-level sharing of the affected databases.