Log data sets usage for recovery

IMS Database Recovery Facility uses RLDS (recovery log data sets) as input when they are available.

IMS Database Recovery Facility uses SLDS (system log data sets) as input in the following situations:

• When no RLDS is available
• In case of an error reading RLDSs

This log usage scheme minimizes the impact of recovery on other IMS activity.

Ensure that every OLDS (online log data set) that contains log records that are required for recovery is archived before you start the recovery process. If an OLDS is required for recovery but it has not been archived, recovery is not started and an error message is issued.

If an error occurs while reading the primary copy of a log data set (either RLDS or SLDS), IMS Database Recovery Facility automatically starts reading from the secondary copy.

If errors occur reading from the copies of an RLDS, IMS Database Recovery Facility automatically starts reading from the SLDS for the interval covering the RLDS.