Understanding Central Logging Concepts

This section does not apply to R/3 Systems running on IBM AS/400 and Microsoft Windows NT hosts. Central logging is not available on these platforms. See below for details on central logging with Windows NT systems.

If you like, you can configure your server to write to a central log as well as to a local log. Central logging requires 2 or more R/3 instance or application servers. A single system is the central system. This system collects the log data from the other instance or application servers. For central logging to work, you must do the following:

• Set the logging parameters in each system profile.

• Start a collection process on the central application server.

• Start a send process on the central system and on each instance.

Central System Log Processes

To maintain a central system log, two processes are required: a send process and a collection process. Each instance uses the send process. From each instance, the send process copies local messages to the central log.

The send process is activated automatically at intervals. Each time a send is activated it forwards all the log messages that were posted since its last activation. After forwarding the local messages, the send process sleeps to save system resources.

The intervals between activations of the send process can be less than one minute or more than 30 minutes. The intervals vary automatically according to the level of log activity on an application server. If many entries were written in the log since the last activation of a process, then the next period of deactivation is correspondingly short.

A central instance uses both a send process and a collection process. The collection process receives messages transferred by the send processes on each instance. The collection process is activated in response to communication requests from send processes. Between communication requests, the collection process sleeps.

Process Status Files

Both the send and the collect system processes maintain a file with the extension pid. The pid file contains the operating system ID (process number) of the process. If a process’s pid file contains -1, the process is not allowed to run. If a process's pid file is absent, the process was either never started or was terminated.

In addition to a pid file, a send process also maintains a file with a sta extension. The sta file contains the file descriptor of the file that the send is processing. The sta file also contains the byte offset up to which the process has processed in the file.

The byte offset is not updated with every system log message processed.

Central Logging with Windows NT

No central system log is kept on Windows NT systems. The processes necessary to maintain a central log are not required. To avoid system warnings regarding the central log, set the R/3 system parameter rslg/collect_daemon/host on your NT system to NONE.

Use the System log ® Choose ® All remote system logs function to read the data from all instances in your R/3 System. If an alert occurs in the Alert monitor, evaluate the affected instance using the Remote SysLog function.