Freeing a Log File with Status U-B or F

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Freeing a Log File with Status U-B or F

If a log file is backed up but still in use (status U-B), some transactions in the log file are still under way, or the log file contains the oldest update that is required for fast recovery. Because a log file with status F has been used in the past, it follows the same rules as for status U-B.

To free a backed up log file that is in use

If you do not want to wait until the transactions complete, take the database server to quiescent mode. See Immediately from Online to Quiescent. Any active transactions are rolled back.
Because a log file with status U-B might contain the oldest update, you must use the onmode -c command to force a full checkpoint.

A log file that is backed up but not in use (status U-B) does not need to be freed. In the following example, log 34 does not need to be freed, but logs 35 and 36 do. Log 35 contains the last checkpoint, and log 36 is backed up but still in use.

34 U-B--   Log is used, backed up, and not in use
35 U-B-L   Log is used, backed up, contains last checkpoint
36 U-B--   Log is used, backed up, and not in use
37 U-C--   This is the current log file, not backed up

Tip:

You can free a logical log with a status of U-B (and not L) only if it is not spanned by an active transaction and does not contain the oldest update.