A HiRDB/Single Server is composed of the following server:

• Single server

The unit controls and monitors execution of the server. The unit can be compared conceptually to a container in which the server is stored.

The single server is the server that manages a database (tables and indexes) and the data dictionaries (dictionary tables) that contain information about the database.

If the server machine on which a HiRDB/Single Server is implemented does not have I/O devices, such as CMT or magnetic tape drive, a server machine equipped with an I/O device can be used as a utility special unit. For example, when multiple HiRDB/Single Servers are used and there is only a limited number of server machines equipped with I/O devices, a utility special unit can be set up. Figure 1-4 shows an example of a HiRDB/Single Server system configuration in which a utility special unit is included.

Figure 1-4 Example of a HiRDB/Single Server system configuration (with a utility special unit)

Explanation

• Server machines 2-4 are not equipped with I/O devices (such as CMT or magnetic tape drive). Because server machine 1 contains an I/O device, it is designated as a utility special unit.
• When source data on CMT or a magnetic tape is to be stored in the database, the I/O device attached to server machine 1 (utility special unit) is used.