Setting up multiple logical partitions

There are several situations in which it is advantageous to have several database partition servers running on the same computer.

This means that the configuration can contain more database partitions than computers. In these cases, the computer is said to be running multiple logical partitions if they participate in the same instance. If they participate in different instances, this computer is not hosting multiple logical partitions.

With multiple logical partition support, you can choose from three types of configurations:

• A standard configuration, where each computer has only one database partition server
• A multiple logical partition configuration, where a computer has more than one database partition server
• A configuration where several logical partitions run on each of several computers

Configurations that use multiple logical partitions are useful when the system runs queries on a computer that has symmetric multiprocessor (SMP) architecture. The ability to configure multiple logical partitions on a computer is also useful if a computer fails. If a computer fails (causing the database partition server or servers on it to fail), you can restart the database partition server (or servers) on another computer using the START DBM DBPARTITIONNUM command. This ensures that user data remains available.

Another benefit is that multiple logical partitions can use SMP hardware configurations. In addition, because database partitions are smaller, you can obtain better performance when performing such tasks as backing up and restoring database partitions and table spaces, and creating indexes.