DB2 Version 9.7 for Linux, UNIX, and Windows

Instances

An instance is a logical database manager environment where you catalog databases and set configuration parameters. Depending on your needs, you can create more than one instance on the same physical server providing a unique database server environment for each instance.

Note: For non-root installations on Linux and UNIX operating systems, a single instance is created during the installation of your DB2® product. Additional instances cannot be created.

You can use multiple instances to do the following:

Multiple instances will require:

The instance directory stores all information that pertains to a database instance. You cannot change the location of the instance directory once it is created. The directory contains:

Terminology:

Bit-width
The number of bits used to address virtual memory: 32-bit and 64-bit are the most common. This term might be used to refer to the bit-width of an instance, application code, external routine code. 32-bit application means the same things as 32-bit width application.
32-bit DB2 instance
A DB2 instance that contains all 32-bit binaries including 32-bit shared libraries and executables.
64-bit DB2 instance
A DB2 instance that contains 64-bit shared libraries and executables, and also all 32-bit client application libraries (included for both client and server), and 32-bit external routine support (included only on a server instance).