DB2 Server for VM: System Administration

Virtual Machine Overview

This section provides an overview of the virtual machines required by the database manager.

You need one or more of the following virtual machines for installation and subsequent use:

1. MAINT. This machine already exists in your VM system.
2. Installation User ID. You need it to use VMSES/E to install, service, and migrate the database manager.
3. Database machine. A database machine is a virtual machine in which the database manager code runs. There can be more than one database machine.

   The database machine owns a database. It provides all database management services for a database. The database machine processes SQL requests from users, and returns the results to the users.

   Note:

   The word "own", in this context, describes the association of the database machine's user ID as the owner of the minidisks that contain the database. Users who want to link to and access minidisks owned by another user must be authorized by the owner or the system administrator.

   The VM database machines can be defined as either a LOCAL resource, which restricts access to users on the same processor, or a GLOBAL resource, which allows access to users on other processors. For more information on defining databases, see VM Directory Control Statements.

4. Service machine. A service machine is required by any processor that does not have its own database machine, and has users who want to access data in either of the following:
   • A DB2 Server for VM database in a Transparent Services Access Facility (TSAF) collection
   • A relational database residing in an SNA network that uses remote unit of work or distributed unit of work support.

   DRDA Remote Unit of Work (RUOW) support was introduced in SQL/DS Version 3 Release 3. DRDA Distributed Unit of Work (DUOW) server support is introduced in DB2 Server for VM Version 5 Release 1. For more information on the DRDA environment, see Chapter 15, Using a DRDA Environment.

   The service machine provides essential support to users by allowing access to a DB2 Server for VM production minidisk. The production minidisk contains files required by the users. For example, the SQLINIT EXEC files that enable ISQL (Interactive Structured Query Language), the DBS utility, and the preprocessors are located on this minidisk.

   For information on installing the service machine and the files that it uses, see the DB2 Server for VM Program Directory.

5. User machine. A user machine is a virtual machine that has read access to the database machine production minidisk.