You only need to start SAPOSCOL yourself the first time that it is started on a host (see Installation and Configuration of SAPOSCOL). Thereafter, SAPOSCOL is automatically stopped and started when the host is shut down and started; this applies irrespective of whether SAP components are running on the corresponding host. A manual stop and restart is only necessary in the following conditions:

• Under UNIX, you start SAPOSCOL with the command saposcol (or saposcol -l).
• Under Windows NT, you start SAPOSCOL by starting the corresponding service by choosing Start → Settings → Control Panel → Services (see SAP Note 0436186).
• You can also start SAPOSCOL in the operating system monitor.

1. If the call finds a SAPOSCOL segment in the shared memory, it takes over its process ID (PID) and the stored data of a SAPOSCOL that may already be running.
2. If no other SAPOSCOL is collecting data, the PID is 0, and SAPOSCOL uses the existing shared memory segment when starting. SAPOSCOL also starts if no shared memory is available.
3. The new SAPOSCOL does not start if it detects that another SAPOSCOL is already collecting data.
4. After it has been started, SAPOSCOL performs an initialization during which it reserves its required space in shared memory. The program calculates the size of this space from the number of available hard disks, CPUs, file systems, and so on. SAPOSCOL writes the contents of the file coll.put (if it exists) to its shared memory segment.
5. The process continues running in the background, and the original program ends.

 Operating System Monitor and Operating System Collector SAPOSCOL initial pages.