Log area not mirrored: System default value

Log area mirrored (software-based): Only use this setting if hardware-based mirroring is not possible. Software-based mirroring reduces the performance of your database system.

In software-based mirroring, the database system writes redo log entries to two log areas in parallel (primary and secondary log area). The database system can only overwrite the log areas when the log entries in the primary log area have been backed up.

Overwrite mode is off:

The database system can only overwrite the log area once the corresponding redo log entries have been backed up. We therefore recommend that you activate the automatic log backup function or perform interactive backups regularly.

Overwrite mode on:

The database system cyclically overwrites the log area without first backing up the redo log entries. This results in gaps in the backup history. This, in turn, means that you can only restore your database up to the time of the last data backup.

Redo log management is on:

System default value

Redo log management is off:

In rare cases, it may make sense to switch off redo log management, for example during a big load job. Note that this interrupts the log backup history. If you have to restore the database after an error, no redo log entries are available for this period of time. Thus you lose the data since the last data backup.