Controlling Log Switching

This topic does not apply to SAP systems running on IBM AS/400 or Microsoft Windows NT hosts. The log processes described in this topic aren’t required on these platforms.

In the central logging, the log changes when the system replaces the old log with the active log. In local logs, log switching occurs when the system begins overwriting the log file.Central log switching is regulated by the rslg/max_diskspace/central parameter. Local log switching is regulated by the rslg/max_diskspace/local parameter.

The rslg/max_diskspace/local and rslg/max_diskspace/central parameters specify the length of log files. If these parameters value are large, switching occurs less frequently than if the value were smaller. Additionally, a large log size can help prevent lost messages in the event that sudden heavy message activity causes rapid switching of the central log.

To control central log switching, set the rslg/max_diskspace/central parameter to the maximum combined length of the current and old central logs. You must set this parameter in the system where the central log resides. The system switches the logs when the active log file size reaches approximately half the value specified in the rslg/max_diskspace/central parameter.

The rslg/max_diskspace/central and rslg/max_diskspace/local parameters do not affect the trace logs used by the log system processes to record their own error messages. These logs are not subject to automatic deletion;you must delete them yourself if you selected them using special options.

For more information on how the system writes log files, see Concepts of System Logging.