Non-recovery option

By specifying a VSO or non-VSO DEDB as nonrecoverable, you can improve online performance and reduce database change logging of your DEDBs.

IMS does not log any changes from a nonrecoverable DEDB, nor does it keep any updates in the DBRC RECON data set. All areas are nonrecoverable in a nonrecoverable DEDB.

Unlike full-function nonrecoverable databases, which support backout, nonrecoverable DEDBs are truly nonrecoverable and cannot REDO during restart or XRF takeover. IMS writes a single log record, X'5951', once for every area at each sync point to indicate that nonrecoverable suppression has taken place.

The X'5951' log and DMAC flags determine the integrity of an area during an emergency restart or XRF takeover. Nonrecoverable DEDB write errors can happen during restart or XRF takeover. If there are errors found in a nonrecoverable DEDB during an XRF takeover or an emergency restart, message DFS3711W is issued and the DEDB is not stopped.

Nonrecoverable DEDBs must register with DBRC. To define a DEDB as nonrecoverable, use the command INIT.DB DBD() TYPEFP NONRECOV. The default is RECOVABL for recoverable DEDB.

Before changing the recoverability of a DEDB, issue a /STOP DB, /STO AREA, or /DBR DB command. To change a recoverable DEDB to a nonrecoverable DEDB, use the DBRC command CHANGE.DB DBD() NONRECOV. To change nonrecoverable DEDB to a recoverable DEDB, use the command CHANGE.DB DBD() RECOVABL.

To restore a nonrecoverable DEDB, use the GENJCL.RECOV RESTORE command. The recovery utility restores the database to the last image copy taken. If the DEDB had been changed from a recoverable DEDB to a nonrecoverable DEDB, the recovery utility will apply any updates from the logs up to the point when the change was made (if no image copy was made after the change to nonrecoverable).