Even though the processes are unique at OS level SAP differentiated between the work processes based on the nature of work.
The process are determined by the instance name DVEBMGS<Instance_No>
For Dialogue instances the work process will be denoted as D01, D02....
D - Dialogue
V - Update
E - Enqueue
B - Back ground
M - Message
G - Gateway
S - Spool
DVEBMGS is only available in the Central instance.
D01 to DN-1 for Dialogue instances.
Central Instance DVEBMGS - 2112111
It hosts all the process and their will be only one central instance in the entire system.
1. DIALOGUE 'D'
It is only the process which communicates interactively with the users. There should be atleast 2 Dialogue work process per instance. Dialogue work process initiates Update, Background and Spool.
2. UPDATE 'V'
It is used to update the transactions in the database. It is initiated by Dialogue process. There should be atleast 1 Update in the entire system. It is also recommended to have an update process for every 5 Dialogue.
3. ENQUEUE 'E'
It is used to provide locks for the records that are going to be updated. It ensures consistency for updates. There will be only 1 Enqueue configured in the system during the installation. It is possible to have more than one enqueue provided they are installed or configured on the central instance.
4. BACKGROUND 'B'
The tasks which are expensive or time consuming are scheduled to run in the background mode non-interactively. There should be atleast 2 background work process in the system
5. MESSAGE 'M'
There should be only 1 message server in the entire R/3 system. It is used to manage all the dispatchers. It is used to load balance the requests to identify the least loaded dispatcher.
It is also used to provide locks to the request that are coming from Dialogue instances.
6. GATEWAY 'G'
It is used to provide a means of communication with SAP and NON-SAP systems. There will be only 1 gateway for each instance.
7. SPOOL 'S'
It is used to print the documents to a printer or output to a fax machine etc. There should be atleast 1 Spool process in the entire system. It is also possible to configure more spool process depending on the print/ spool volume.
Dialogue - Interactive - 2 per instance - Initiate update, spool and btc (background)
Update - Non-Interactive - 1 per system - Initiated by dialogue
Enqueue - Provides consistency for updates - 1 per system and can be increased
Depending upon the update requests but needs to increase only on the
Central instance for optimal performance.
Background - Non-Interactive - 2 per system - Initiated by dialogue, Time consuming
And long running jobs are scheduled to run in the background mode.
Message - Used during load balancing. It also procures lock from enqueue server
To serve the requests that is coming from dialogue instances. Only 1
Gateway - It provides an interface to communicate between SAP and NON-SAP
Systems. 1 Gateway per instance.
Spool - It is only the process that outputs the documents to printers, fax etc.
It is initialized by Dialogue and BTC. Atleast 1 spool per system.