SAP BASIS Instances
SAP Instances have three types –
SAP System = Dialog Instance + Central Instance + Database Instance.
1. Dialogue Instance
There is a dialogue instance in the application layer. SAP BASIS Instances | iiQ8 Education For a given system, the application layer can have a greater number of dialogue instances. It is used to maintain and distribute the server’s load.
There may be a dialogue instance on a different host. Hardware resources, a dispatcher, and work processes make up a dialogue instance. If the number of dialogue instances rises, so do hardware resources, dispatchers, work processes, and the number of concurrent user logins.
2. Central Instance
With some additional duties, the central instance can serve as the dialogue instance. Enqueue process will identify central and dialogue instances. Enqueue process is only present in the central instance.
Enqueue and message servers can be found in the central instance. Before accessing a database through a message server, all Dialog instances first connect with the central instance. When an instance is started, the dispatcher process tries to connect to the message server. in order to announce the services (DIA, BTC, SPO, UPD, etc.). Using the enqueue service, the locking table can be handled centrally. For a single SAP system, there will only be one instance.
3. Database Instance
The database instance responds to the central instance’s requests. Based on the user’s demands, the central instance delivers the requests to the database instance. Users are served by the database instance just as the enqueue server offers the lock management system.
We can use 100 Numbers of Instances in SAP System. It will start from 00 to 99.
Central Instance
Dialog Instance
SAP Transport Management System – TMS (STMS)
SAP BASIS Instances
7 Number of Workprocess in SAP System.
Dialog Workprocess (Minimum 2 numbers of dialog workprocess required in a SAP System)
Background Workprocess (Minimum 1 number of dialog workprocess required in a SAP System)
Update Workprocess (Update and Update2 Workprocess) (Minimum 1 number of dailoge workprocess required in a SAP System)
Enque Workprocess (Minimum 1 number of dailoge workprocess required in a SAP System)
Spool Workprocess (Minimum 1 number of dailoge workprocess required in a SAP System)
Gateway Workporcess (Minimum 1 number of dailoge workprocess required in a SAP System)
Message Workprocess (Minimum 1 number of dailoge workprocess required in a SAP System)
SAP instances are defined during the installation of the SAP system.
Note
The term “instance” is often used synonymously with “server” or “application server” in the SAP system. This depends on the selected installation environment. You can install multiple instances on one application server.
An SAP instance defines a group of resources such as memory, work processes and so on, usually in support of a single application server or database server within a client/server environment. Application servers share the same memory areas and are controlled by the same dispatcher process.
An SAP instance is handled by CCMS as a unit. A user logs on to the SAP system using an instance.
An SAP system can consist of one or more instances, such as an SAP system with a single instance with only one central server or a client/server system with two or more separate instances.
For each SAP instance:
- Separate directories are defined on the UNIX, AS/400, or Microsoft Windows NT server on which the instance is to run
- Shared file systems can be used
- Entries are created in operating system configuration files (/etc/services, /etc/sapconfig…)
- Communication entries are created in the host
- Start and system profiles are created
- Operating system users are installed
Note
An SAP instance is not assigned automatically to an operation mode.
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