Recording and controlling log information

As IMS operates, it constantly records its activities in the IMS logs. After you have initialized DBRC, it participates in the IMS logging process by recording and controlling information about logging activities in the RECON data set.

The IMS logs contain information about:

The IMS logs consist of the:

The following figure shows the log data sets and restart data set (RDS) that IMS produces and the RECON data set that DBRC creates and maintains.
Figure 1. Logs produced for recovery and restart
begin figure description. This figure shows an overview of the logging process in an IMS online environment. It illustrates IMS writing log records to the log data sets, IMS writing system checkpoint ID information to the restart data set, and DBRC writing records to the RECON data set. end figure description.
Related reading:

After you have initialized DBRC, it participates in the IMS logging process by recording and controlling information about logging activities. This information is recorded in the RECON data set. If you want DBRC to control the recovery of your database data sets (DBDSs), you must register them with DBRC.

DBRC automatically records many items in the RECON data set, including:

IMS uses this information for restarting itself and for database recovery jobs (if the databases are registered with DBRC). DBRC also tracks the archiving requirements of the OLDS and, if requested, generates and submits the JCL for archiving jobs.

DBRC also provides unit-of-recovery management for all attached subsystems. DBRC provides information about these units of recovery for batch backout, dynamic backout, partial backout, and restart.

For logs produced by batch systems, you are not required to use DBRC. The advantage of using DBRC for batch jobs is that DBRC records information about all the log data sets that are produced by batch jobs and prevents batch update jobs from executing if you specify a dummy or null log data set.

Attention: If registered databases are updated without DBRC control, DBRC cannot correctly control recovery for the databases and database integrity can be jeopardized.