Background documentation The System Log 

The SAP System logs all system errors, warnings, user locks due to failed logon attempts from known users, and process messages in the system log. There are to two different types of logs created by the system log:

·  Local Logs

·  Central Logs

Use transaction SM21 to access the system log output screen. With this transaction, you can read any of the messages that are contained in the system logs. You can modify the view to meet your needs.

Local Logs

Each SAP System application server has a local log that receives all the messages output by this server. The system log records these messages in a circular file on the server. When this log file reaches the maximum permissible length, the system log overwrites it, starting over from the beginning. (The location of the local log is specified in the rslg/local/file profile parameter.)

Central Logs

We recommend that you also maintain a central log file on a selected application server. Each individual application server then sends its local log messages to this server. The server that you designate to maintain the central log collects the messages from the other application servers and writes these messages to the central log.

The central log consists of two files: the active file and the old file. (The location of the active file is specified in the rslg/central/fileprofile parameter; the location of the old file is specified in the rslg/central/old_file.)

The active file contains the current log. When it reaches the maximum size, the system performs a "log file switch". It deletes the old log file, makes the previously active file the “old” file, and creates a new active file. The switch occurs when the size of the active log file is half the value as specified in the rslg/max_diskspace/central parameter. (Note: the SAP System does not support the saving of old system log files. If you want to save old logs, then you must archive them yourself.)


If you use Windows NT or AS/400, then note the following:

-  Central logging is not available on the Windows NT and AS/400 platforms.

-  Per default, the profile parameter rslg/collect_daemon/host should be set correctly. However, if you receive warnings, then make sure that this parameter is set to NONE.

-  For these platforms, you can use the All remote syslogs function from transaction SM21 to read the data of all the instances in your SAP System. In the alert monitor, if you receive an alert, you can use the Remote syslog function to analyze the affected instance.

Profile Parameters and File Locations

The table below shows some of the profile parameters for the system log along with their standard values:

Profile Parameters and File Locations for the System Log





Specifies the location of the local log on the application server.



Specifies the application server that maintains the central log.

<hostname of main instance>


Specifies the location of the active file for the central log on the application server.



Specifies the location of the old file for the central log on the application server.



Specifies the maximum length of the local log.

500,000 bytes


Specifies the maximum length of the central log.

2,000,000 bytes


This is not a complete list. There are additional profile parameters that refer to the system logs; they all begin with rslg*. However, we do not discuss them all here. You can use the transaction RZ11 to access the rest of the parameters.

For more information, see System log.