OLDS recovery

IMS automatically closes the OLDS during normal shutdown or during emergency restart. You must close an OLDS before you can archive it or use it as input to any utility.

You must close the OLDS using the Log Recovery utility in either of the following circumstances:

• When an emergency restart fails and, rather than performing another emergency restart, you perform a cold start
• When IMS does not close the OLDS because IMS detected a write error (single logging only)

The Log Recovery utility recovers the OLDS from the following types of errors:

• An I/O error while reading the input log data set
• An error in the log record
• A sequence error in the log record, the log block, or the OLDS write time stamp

To recover the OLDS, the Log Recovery utility does the following:

• In CLS mode, the utility closes an input OLDS from information in the WADS if IMS cannot close it because of a system failure. Otherwise, the utility closes the OLDS from the OLDS used immediately after the OLDS in error. The utility uses the immediately prior OLDS, if any, to establish a base point for close processing, using the last block sequence number.

  If dual logging is in effect, IMS must close both OLDSs. If IMS successfully closes the logs, you do not need to use the Log Recovery utility.

• In DUP mode, the utility reads an OLDS and duplicates all readable records on a log.
• In REP mode, the utility reads the interim log created in DUP mode, copies good log blocks, and replaces error blocks with good ones based on information that you specify in control statements. The output log data set is a usable OLDS.

If the OLDS being recovered has not been closed (DBRC shows a stop time of zero), you must use the output from REP mode as input to CLS mode.