Recovering from being out of space in active logs

The available space in the active log is finite, so the active log might fill to capacity for one of several reasons. For example, delays in offloading and excessive logging can fill the active log. You can recover from out-of-space conditions in the active log.

Symptoms

The following warning message is issued when the last available active log data set is 5% full:

DSNJ110E - LAST COPYn ACTIVE LOG DATA SET IS nnn PERCENT FULL

The Db2 subsystem reissues the message after each additional 5% of the data set space is filled. Each time the message is issued, the offload process is started. IFCID trace record 0330 is also issued if statistics class 3 is active.

If the active log fills to capacity, after having switched to single logging, Db2 issues the following message, and an offload is started. 

DSNJ111E - OUT OF SPACE IN ACTIVE LOG DATA SETS

The Db2 subsystem then halts processing until an offload is completed.

Causes

The active log is out of space.

Environment

An out-of-space condition on the active log has very serious consequences. Corrective action is required before Db2 can continue processing. When the active log becomes full, the Db2 subsystem cannot do any work that requires writing to the log until an offload is completed. Until that offload is completed, Db2 waits for an available active log data set before resuming normal Db2 processing. Normal shutdown, with either a QUIESCE or FORCE command, is not possible because the shutdown sequence requires log space to record system events that are related to shutdown (for example, checkpoint records).

Resolving the problem

Operator response:
  1. Ensure that the offload is not waiting for a tape drive. If it is, mount a tape. Db2 then processes the offload task.
  2. If you are uncertain about what is causing the problem, enter the following command: 
    -ARCHIVE LOG CANCEL OFFLOAD
    This command causes Db2 to restart the offload task. Issuing this command might solve the problem.
  3. If issuing this command does not solve the problem, determine and resolve the cause of the problem, and then reissue the command. If the problem cannot be resolved quickly, have the system programmer define additional active logs until you can resolve the problem.
System programmer response: Define additional active log data sets so that Db2 can continue its normal operation while the problem that is causing the offload failures is corrected.
  1. Use the z/OS® command CANCEL to stop Db2.
  2. Use the access method services DEFINE command to define new active log data sets.
  3. Run utility DSNJLOGF to initialize the new active log data sets.
  4. Define the new active log data sets in the BSDS by using the change log inventory utility (DSNJU003).
  5. Restart Db2. Offload is started automatically during startup, and restart processing occurs.
Recommendation: To minimize the number of offloads that are taken per day in your installation, consider increasing the size of the active log data sets.