Manual and continuous logical-log backups

You can manually back up logical logs or you can enable continuous logical-log backup.

A manual logical-log backup backs up all the full logical-log files and stops at the current logical-log file. You must monitor your logical logs carefully and start logical-log backups as needed.

To find out if a logical-log file is ready to be backed up, check the flags field of onstat -l. After the logical-log file is marked as backed up, it can be reused. When the flags field displays any of the following values, the logical-log file is ready to be backed up:

U------
U-----L

The value U means that the logical-log file is used. The value L means that the last checkpoint occurred when the indicated logical-log file was current. The value C indicates the current log. If B appears in the third column, the logical-log file is already backed up and can be reused.

U-B---L

The flag values U---C-L or U---C-- represent the current logical log. While you are allowed to back up the current logical log, doing so forces a log switch that wastes logical-log space. Wait until a logical-log file fills before you back it up.

If you turn on continuous logical-log backup, the database server backs up each logical log automatically when it becomes full. If you turn off continuous logical-log backup, the logical-log files continue to fill. If all logical logs are filled, the database server hangs until the logs are backed up. You can start continuous logical log backups by setting the ALARMPROGRAM configuration parameter in the onconfig file or by running an ON-Bar or ontape command.