Locking impacts of HALDB Online Reorganization
To maintain partition integrity and recoverability during an online reorganization of a HALDB partition, HALDB Online Reorganization requests a very large number of locks for each UOR from the active lock manager, either the program isolation lock manager or the Internal Resource Lock Manager (IRLM) component.
When IRLM is the lock manager, an online reorganization can incur a significant number of IRLM lock structure accesses per second, especially if the reorganization is running with the RATE(100) specification. Also, if the database is shared by multiple IMS systems when IRLM is used, the online reorganization function requests global locks, just as application programs do.
- Use the IBM® System z® Coupling
Facility Structure Sizer Tool (CFSizer) to
model the additional coupling facility activities to ensure that your
coupling facility configuration is capable of handling the extra load
introduced by the online reorganizations:
- For IRLM 2.1 with
PC=NOspecified, each additional 1000 concurrently held locks requires 256 KB of ECSA storage. - For IRLM 2.2, each additional 1000 concurrently held locks requires 540 KB obtained from IRLM private storage. No increase in ECSA storage is necessary.
- For IRLM 2.1 with
- Review your LOGL latch contention rate, OLDS logging rate, IRLM lock structure access, and DBBP (for OSAM) latch contention.
CFSizer is
available for you to use at the following website: www.ibm.com/servers/eserver/zseries/cfsizer/,
or search for CFSizer
at
the IBM website: www.ibm.com.