OLAP Setup and User's Guide

Allocating Memory

For optimum performance, the memory in the machine on which you install DB2 OLAP Server should not be over committed. The memory required by the operating system, application working sets, and multidimensional storage manager and DB2 caches and buffer pools should not exceed the physical memory in the machine.

Each multidimensional database requires memory to be allocated for:

• Data cache
• Index cache

In addition, a DB2 database requires memory to be allocated for buffer pools.

Determining the best allocation of memory is often an iterative process. Start with the minimum memory requirements for each component and then tune up as necessary. You can use the following guidelines as a starting point:

• Allocate 1 MB of memory for the multidimensional database index cache.
• Allocate 40 percent of the remaining memory for the DB2 buffer pools.
• Allocate 20 percent of the remaining memory for the multidimensional data cache.
• Leave the remaining memory as spare memory.