SMS has two types of server components — service and thread. Service components are processes that run as Windows NT services and that provide SMS functionality. At installation they are set to start automatically and can be started and stopped through Control Panel, Services.
Thread components function as part of the SMS Executive Service. They also work internally to accomplish the tasks that make SMS such a powerful product. You can start and stop thread components and enable logging using the SMS Service Manager under Tools in the SMS Administrator console.