Log Recovery utility (DFSULTR0)

The Log Recovery utility produces a usable log data set from an OLDS or SLDS that contains read errors or was not properly closed.

The Log Recovery utility has four modes of operation:

• CLS mode, to close an OLDS
• DUP mode, to create:
  • Create an interim log containing error records
  • Create a closed batch SLDS containing an end-of-file mark
• REP mode, to:
  • Read the interim log
  • Replace the error records with data that you specify
  • Create a new log
• PSB mode, to produce a report of active PSBs from the input log

When IMS opens the input logs, DBRC validates them, ensuring that the data set name and volume serial numbers agree with those in the RECON data set. For log recovery, DBRC requires that the entire log data set be specified as input to the IMS Log Recovery utility, not just selected volumes. For a closed SLDS, DBRC requires only the last volume as input to the Log Recovery utility.

When IMS opens the output logs, it calls DBRC to do the following:

• Create an IPRIOLDS record (and ISECOLDS record if you are using dual logging) using the time stamp of the input log and the data set name from the job file control block of the output log. Applies to DUP mode.
• Create new OLDSs from interim OLDSs. Applies to REP mode.

DBRC issues the GENJCL.CLOSE command to generate a job to run the Log Recovery utility. When you issue this command, specify the subsystem ID of the IMS subsystem that created the OLDS to be closed. You can also specify the OLDS to be closed. If you do not specify an OLDS, DBRC closes the most recent, open OLDS. You can issue the GENJCL.CLOSE command using the Recovery Control utility or as an IMS command.

When IMS reads the write-ahead data sets (WADS), the Log Recovery utility might issue the DFS3253W warning message to explain the MVS messages that VSAM issues in the job log.