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.
You should explicitly terminate the collect and send system log processes as part of any shutdown or reboot of the host operating system. If you start processes with the start-up profile, the processes are shut down automatically by a system shutdown. The log system processes are not affected by an abnormal termination of the SAP System. Abnormal termination is termination of the work and dispatcher processes.
Should you need to shut down a log process with an operating system command, you can have the process perform a normal or an expedited orderly termination. An example of such an operating system command is the UNIX kill command.
Using a terminate option starts a normal termination. The affected process finishes any processing that is under way. The process then terminates rather than idling. In this case, a send process, for example, attempts to finish processing all new messages in a log before terminating.
Using a terminate option a second time starts an expedited termination.An active process completes its current unit of work and then terminates. A send process, for example, finishes sending the current message before terminating.
An inactive process is immediately terminated by a terminate command. The process will not restart automatically until the you reboot the system or manually restart the process.
If you shutdown a system without terminating the collect process or if the system crashes, the current central log may become corrupted. Corruption occurs if the collect process is writing a message to the log file when the shutdown occurs.
If a log becomes corrupted by an incomplete message or other problem, you must manually correct the problem by repairing or deleting the log file. The log system processes respond with error messages to a corrupted file.
Locking a process prevents it from being started. Send processes, in particular, do not start automatically if you lock them. You should lock a process when you do not want system log messages forwarded or if the entire SAP System is running in a single instance. Use the following procedure to lock processes:
1. Stop the process that you wish to lock.
2. Enter the value -1 in the process's pid file.