DB2 Server for VSE & VM: Interactive SQL Guide and Reference

Components of the Relational Database Management System

Figure 1 depicts a typical configuration with one database and two users.

Figure 2 depicts a typical configuration with one database, one batch partition user, and a CICS^(R) partition with several interactive users.

Figure 1. Basic Components of the RDBMS in VM/ESA

Figure 2. Basic Components of the RDBMS in VSE/ESA

The database is composed of :

• A collection of data contained in one or more storage pools, each of which in turn is composed of one or more database extents (dbextents). |A dbextent is a VM minidisk or a VSE VSAM cluster.
• A directory that identifies data locations in the storage pools. There is only one directory per database.
• A log that contains a record of operations performed on the database. A database can have either one or two logs.

The database manager is the program that provides access to the data in the database. In VM it is loaded into the database virtual machine from the production disk. In VSE it is loaded into the database partition from the DB2 Server for VSE library.

The application server is the facility that responds to requests for information from and updates to the database. It is composed of the database and the database manager.

The application requester is the facility that transforms a request from an application into a form suitable for communication with an application server.