Rollforward overview

The simplest form of the DB2 ROLLFORWARD DATABASE command requires only that you specify the alias name of the database that you want to rollforward recover. For example:

   db2 rollforward db sample to end of logs and stop

In this example, the command returns:

                                 Rollforward Status

 Input database alias                   = sample
 Number of nodes have returned status   = 1

 Node number                            = 0
 Rollforward status                     = not pending
 Next log file to be read               =
 Log files processed                    =  -
 Last committed transaction             = 2001-03-11-02.39.48.000000

DB20000I  The ROLLFORWARD command completed successfully.

The following is one approach you can use to perform rollforward recovery:

1. Invoke the rollforward utility without the STOP option.
2. Invoke the rollforward utility with the QUERY STATUS option

   If you specify recovery to the end of the logs, the QUERY STATUS option can indicate that one or more log files is missing, if the returned point in time is earlier than you expect.

   If you specify point-in-time recovery, the QUERY STATUS option will help you to ensure that the rollforward operation has completed at the correct point.

3. Invoke the rollforward utility with the STOP option. After the operation stops, it is not possible to roll additional changes forward.

An alternate approach you can use to perform rollforward recovery is the following:

1. Invoke the rollforward utility with the AND STOP option.
2. The need to take further steps depends on the outcome of the rollforward operation:
   • If it is successful, the rollforward is complete and the database will be connectable and usable. At this point it is not possible to roll additional changes forward.
   • If any errors were returned, take whatever action is required to fix the problem (for example, if there is a missing logfile, find the log file, or if there are retrieve errors, ensure that log archiving is working). Then reissue the rollforward utility with the AND STOP option.

When the rollforward utility is invoked:

• If the database is in rollforward pending state, the database is rolled forward. If table spaces are also in rollforward pending state, you must invoke the rollforward utility again after the database rollforward operation completes to roll the table spaces forward.
• If the database is not in rollforward pending state, but table spaces in the database are in rollforward pending state:
  • If you specify a list of table spaces, only those table spaces are rolled forward.
  • If you do not specify a list of table spaces, all table spaces that are in rollforward pending state are rolled forward.

When you first create a database, it is enabled for circular logging only. This means that logs are reused, rather than being saved or archived. With circular logging, rollforward recovery is not possible: only crash recovery or version recovery can be done. Archived logs document changes to a database that occur after a backup was taken. You enable log archiving (and rollforward recovery) by setting the logarchmeth1 database configuration parameter to a value other than its default of OFF. When you set logarchmeth1 to a value other than OFF, the database is placed in backup pending state, and you must take an offline backup of the database before it can be used again.