OLAP Setup and User's Guide

Configuring Hardware

When you select your server hardware, remember that the server must run both DB2 and DB2 OLAP Server. Select hardware that has the fastest available processor and bus configuration, and that has I/O characteristics that are optimal for DB2.

Use the following additional guidelines when you configure the hardware for DB2 OLAP Server:

• The computer must have enough physical memory to run both servers. DB2 needs memory to service the DB2 heaps, buffers, and buffer pools. DB2 OLAP Server needs memory to service data and index caches.
• To optimize the use of your disk drives, configure DB2 to use multiple fast physical devices and a fast input/output (I/O) controller. This avoids the contention and excess head movement that occurs when the same physical devices are used for DB2 OLAP Server data. It is especially important that the fact table and the fact table index are stored on separate physical devices.
• Avoid using redundant arrays of independent disks (RAID arrays) and RAID controllers. RAID arrays and controllers can severely impact DB2 I/O performance.

The DB2 OLAP Server calculation process is partly multithreaded; it does not take full advantage of shared multiprocessor (SMP) power during calculation. You can use the optional Partitioning Option add-on feature to exploit SMP parallelism. One large cube can be split into several smaller cubes that are loaded and calculated in parallel.

Query processing in DB2 OLAP Server is fully multithreaded; after the cube is calculated, multiple users can run concurrent queries with performance that is better than performance you see during calculation.