Resolving postponed units of recovery

You can postpone some of the backout work that is associated with long-running units of work during system restart by using the LBACKOUT subsystem parameter. By delaying such backout work, the Db2 subsystem can be restarted more quickly.

About this task

If you specify LBACKOUT = YES or LIGHT, you must use the RECOVER POSTPONED command to resolve postponed units of recovery.

Procedure

To complete postponed backout processing on all units of recovery:

Use the RECOVER POSTPONED command.

You cannot specify a single unit of work for resolution. This command might take several hours to complete depending on the content of the long-running job.

In some circumstances, you can elect to use the CANCEL option of the RECOVER POSTPONED command. This option leaves the objects in an inconsistent state (REFP) that you must resolve before using the objects. However, you might choose the CANCEL option for the following reasons:

You determine that the complete recovery of the postponed units of recovery will take more time to complete than you have available. You also determine it is faster to either recover the objects to a prior point in time or run the LOAD utility with the REPLACE option.
You want to replace the existing data in the object with new data.
You decide to drop the object. To drop the object successfully, complete the following steps:
1. Issue the RECOVER POSTPONED command with the CANCEL option.
2. Issue the DROP TABLESPACE statement.
You do not have the Db2 logs to successfully recover the postponed units of recovery.

Example

Output from the RECOVER POSTPONED command consists of informational messages. In the following example, backout processing was performed against two table space partitions and two index partitions:

Figure 1. Example of output from RECOVER POSTPONED processing

DSNV435I ! RESOLUTION OF POSTPONED ABORT URS HAS BEEN SCHEDULED
DSN9022I ! DSNVRP 'RECOVER POSTPONED' NORMAL COMPLETION
DSNR047I ! DSNRBMON POSTPONED ABORT BACKOUT
 PROCESSING LOG RECORD AT RBA 00000000000002055000 TO RBA 00000000000001E6A20E
DSNR047I ! DSNRBMON POSTPONED ABORT BACKOUT
 PROCESSING LOG RECORD AT RBA 00000000000002049000 TO RBA 00000000000001E6A20E
DSNI024I ! DSNIARPL BACKOUT PROCESSING HAS COMPLETED
      FOR PAGESET DSNDB04 .I PART 00000004.
DSNI024I ! DSNIARPL BACKOUT PROCESSING HAS COMPLETED
      FOR PAGESET DSNDB04 .PT PART 00000004.
DSNI024I ! DSNIARPL BACKOUT PROCESSING HAS COMPLETED
      FOR PAGESET DSNDB04 .I PART 00000002.
DSNI024I ! DSNIARPL BACKOUT PROCESSING HAS COMPLETED
      FOR PAGESET DSNDB04 .PT PART 00000002.

If a required page cannot be accessed during RECOVER POSTPONED processing, or if any other error is encountered while attempting to apply a log record, the page set or partition is deferred and processing continues. Db2 writes a compensation log record to reflect those deferrals and places the page in the logical page list. Some errors that are encountered during recovery of indexes cause the entire page set to be placed in the logical page list. Some errors halt the construction of the compensation log and mark the page set as RECP.