HiRDB parallel server configuration

A HiRDB parallel server configuration is composed of multiple units (multiple servers). The following figure shows the configuration of a HiRDB parallel server configuration.

Figure 1-5 HiRDB parallel server configuration

[Figure]

Explanation

This HiRDB parallel server configuration consists of three server machines.
In the configuration in this example there are multiple front-end servers.
Two back-end servers are provided per server machine.

Organization of this subsection: (1) Unit; (2) System manager (MGR); (3) Front-end server (FES); (4) Dictionary server (DS); (5) Back-end server (BES)

(1) Unit

A HiRDB parallel server configuration consists of the following types of servers:

System manager
Front-end server
Dictionary server
Back-end server

A unit controls and monitors server execution and manages communication between servers. A unit can be compared conceptually to a container in which servers are stored.

(2) System manager (MGR)

The system manager is the server that controls HiRDB startup and termination. It also manages system configuration information and detects server errors.

One system manager is required per system.

(3) Front-end server (FES)

A front-end server determines the procedure by which databases are accessed and provides directives to back-end servers on the contents of tasks that are to be executed. A front-end server also analyzes SQLs, optimizes SQLs, provides processing instructions to back-end servers, and edits search results.

Each system must have at least one front-end server (up to a maximum of 1,024 front-end servers). A configuration in which there are multiple front-end servers is called a multi-front-end server configuration. When SQL processing results in a high CPU workload that exceeds the processing capability of a single front-end server, a multi-front-end server configuration is appropriate. A multi-front-end server configuration can distribute the processing load among the machines on which front-end servers are running.

(4) Dictionary server (DS)

The dictionary server provides batch management of the data dictionaries (dictionary tables) that contain database definition information.

Each system requires one dictionary server.

(5) Back-end server (BES)

A back-end server manages the database. On the basis of execution directives received from front-end servers, the back-end servers access and lock the database and perform computational operations. Back-end servers also sort, merge, and join search results.

At least one back-end server is required per system (up to a maximum of 16,382 back-end servers). When multiple back-end servers are provided, a table can be divided among them so that it can be managed on a split basis.

Performance can be improved in a HiRDB parallel server configuration by providing back-end servers that do not provide database management but instead are dedicated specifically to processing high-overhead operations, such as sorting and joining. Such back-end servers are called floatable servers. The following figure shows a floatable server.

Figure 1-6 Floatable server