Log Settings

You can use log settings to configure the most important properties of transaction logging.

Log Settings
Name	Description
Log mode	Specifies whether the database system supports software-based mirroring of the log volumes. The log volumes are not mirrored Default value The log volumes are mirrored (software-based) Only use this setting if hardware-based mirroring, for example using a RAID system, is not possible. Software-based mirroring reduces the performance of your database system.. When software-based mirroring is activated, 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 with new log entries after the log entries in the primary log area have been backed up.
Overwrite mode for the log area	Specifies whether the database system can overwrite redo log entries in the log area even if they have not been backed up. 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 regularly carry out interactive log backups. 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. Caution Switching on overwrite mode interrupts the backup history. If you have to restore the database after an error, no redo log entries are available for this period of time, and you lose all data since the last data backup. End of the caution. If overwrite mode is on and you switch it off, you then have to carry out a complete data backup.
Redo log management	Specifies whether the database system writes redo log entries. ON Default value The system writes redo log entries. OFF Caution Do not switch redo log management off in normal database operation. When redo management is switched off, the system does not write regular savepoints. This means that if you restart your database after a database crash, you lose all data since the last savepoint. If you have to restore your database, you can only restore it to the state of the last data backup. Only consider switching redo log management off in special situations, for example in a test system or during a large load job. End of the caution. If redo log management is off and you switch it back on, you then must carry out a complete data backup.

Note Note

In addition to the log settings, there are several database parameters that influence logging.

More information: Database Parameters

End of the note.

More Information

Concepts of the Database System, How Databases Log Data Changes

Database Studio, Changing Log Settings

Database Manager CLI, param_addvolume

Database Administration in CCMS, Log Area