1. Make sure that enough backup media (that is, tapes or disk space, for example) is available for the backup.
2. Check that the backup has completed successfully. Refer to Checking Logical-Log Backup Result with Message Log.
3. Set LBU_PRESERVE parameter in ONCONFIG file

This is the most important prevention against emergency logical-log backups. If other measures fail, this parameter always prevents the logical log filling completely. It specifies how many logical-log files the database server always preserves (that is, avoids writing logging data to). Set it as follows:

LBU_PRESERVE 1



Another name for this parameter is the "Logs-Full High-Water Mark." It works as follows (note that its default value is 0).

If LBU_PRESERVE is set to 1 , all sessions performing update, delete, and insert operations stop when the last but one logical-log file has filled up. You see the following in the message log:

Logical log files are almost full - backup is needed

Once the logical log has been backed up, processing can continue.

You can view the message log with SAPDBA. Refer to System Information. To find the location of the Informix message log on your system, see the MSGPATH parameter in the ONCONFIG file.

4. Set ALARMPROGRAM parameter ( ON-Bar and ON-Archive )

You can use this parameter to specify the path to an event-handling program, such as logevent.sh (for ON-Archive ) or log_full.sh ( ON-Bar ). The scripts automatically back up the logical log. You set ALARMPROGRAM in the ONCONFIG file.

For more information, see:

- Choosing Automatic Logical-Log Backup (ON-Archive)

- Choosing Continuous or Manual Logical-Log Backup (ON-Bar)

5. Use SAP scripts ( ON-Archive )

You can be sure that your logical log does not fill up, which means that the database stops processing and you have to perform an emergency logical-log backup.