Sequence of Startup
The SAP System comprises of Database Instance, Central Services (Message server, Enqueue) and finally the multiple Dialog Instances (ABAP Work Process). The sequence of startup is extremely important. Starting the processes of sequence will result in an inconsistent state and may spawn zombie processes on the OS which will have to killed.
• To startup the SAP system , you should login to SAP with the <sid>adm OS user.
• The <sid>adm OS user belongs to the Unix Group called sapsys on the Unix OS.
• The <sid>adm OS users belongs to the Windows Group called SAP_<sid>_GlobalAdmin and Administrators Group.
• The underlying element of the SAP system is the database instance. Therefore this has to be started first.
• If Central Services has been setup, this has to be started next. This means that the Enqueue Service and the Message service should be started.
• An independent program called SAP OS Collector (saposcol) is started along with the remaining ABAP work processes in the Central Instance. The dispatcher work process is started next.
• Saposcol collects statistical data from the operating system such as CPU and Memory usage parameters
• Finally, the individual dialog instances can be started. There is no dependency between the dialog instances
Role of SAP profiles in startup
• Each SAP instance , whether it is application instance or a dialog instance , has three profiles.
• The three profiles and the sequence in which they are read :
– START PROFILE ( START<Instance><Instance Number>_<Host name> )
– DEFAULT PROFILE (DEFAULT.PFL)
– INSTANCE PROFILE (SID<Instance><Instance Number>_<Host name> )
• The start profile is read by the sapstartsrv process and inputs are provided on the SAP system ID and number, as well the physical filepaths of the sap executables for starting message service and enqueue service.
• Once the dispatcher work process is started, the Default Profile file is read. This file provides the necessary information to the dispatcher on the memory and sap application performance settings required to run the instance.
• The instance profile is the last file to be read. Any settings in the instance profile file will override the settings in the default profile file.
