Process Flow on Starting & Stop SAP Instance

Flow and processes on starting up SAP

Starting an SAP System is performed in a number of steps and is the task of the
operating system user adm.

Start the database:
•The underlying element of the entire SAP system is the database. Before the
SAP instances are started, this must have operational status. The database is
therefore always started as the first step.

Start the central instance:
•Next, the operating system collector SAPOSCOL is started, this program collects data
about operating system resources and makes this data available through the
shared memory of all SAP instances.

Follow by starting up message server and the dispatcher and its work processes.

The dispatcher also starts the Internet Communication manager (ICM) and the
SAP Web AS Java (if it is installed).

When the instances are started, SAP Service reads which processes (message
server, dispatcher) are to be started from the instance-specific start profile. These profiles are read by the dispatcher, which starts the work processes and creates the instance-specific configuration.

After the instance has been successfully started, all work processes connect to
the database.