Archiving an OLDS

Run the Log Archive utility (DFSUARC0) to archive an OLDS to an SLDS so that IMS can reuse the OLDS. How frequently you should archive depends on the load on the subsystem and the number of log records written to the OLDSs.

The Log Archive utility always produces an SLDS. The SLDS contains all log records that are required for both database recovery and for online IMS restart.

You can ask the Log Archive utility to produce an RLDS in addition to an SLDS. The RLDS contains only those log records that are required for database recovery.

If you request an RLDS, information about the output RLDS data sets is recorded in the PRILOG record in the RECON data set and information about the SLDS data sets is recorded in the PRISLD record. If you do not request an RLDS, the same information about the SLDS data sets is recorded in both the PRILOG and PRISLD records.

If there is a secondary OLDS, or if you request that dual logs be produced from a single OLDS, the information about the secondary-log output is recorded in corresponding SECLOG and SECSLD records.

Important: Log data sets that are output from IMS batch jobs are technically SLDSs, but the information about them is recorded in the PRILOG and SECLOG records.

Run the Log Archive utility by issuing the GENJCL.ARCHIVE command. DBRC then determines which OLDSs are full, and generates the appropriate JCL.

Related reading:  See member DFSDFxxx in IMS Version 15 System Definition for more information on the ARCHDEF statement and automatic archiving.

Recommendation: Whether you use automatic archiving or invoke archiving yourself, make sure the archive jobs run as quickly as possible. The online subsystem only reuses an OLDS after it has been archived. If the archive job is not run and all the OLDS become full, the online subsystem waits. One way to ensure that archive jobs run quickly is to use an initiator that runs with a fairly high priority and is not used by many other users. This ensures that the archive jobs do not remain on the internal reader queue for too long.

If DBRC has marked an OLDS in the RECON data set as having errors, the GENJCL function does not submit it for archiving. If one of a pair of OLDSs has been destroyed or is unavailable, you can choose to mark it in the RECON data set as having errors.

The following references point to where you can find more information about archiving log records.

Related reading: 

  • See IMS Version 15 Operations and Automation for more information about automatic, manual and custom archiving of log records.
  • See IMS Version 15 System Utilities for more information about specifying entry points and running the Log Archive utility.
  • Refer to IMS Version 15 Exit Routines for more information about the Log Archive and the Logger exit routines.