DB2 Performance Features in DB2 V9 for z/OS – Part 13

Lucky 13 -Making Buffer Pool Changes with WLM

With all those year-end jobs running and the system already at 100% utilization there are not too many options for improving DB2 performance and getting things to run faster.

In DB2 Version 9, one of the new features that can be leveraged to improve DB2 performance is increasing your buffer pool with the Workload Manager (WLM) facility. Even if the system is already at 100% utilized, the important jobs need to get done and giving DB2 more resources is usually the best way to improve DB2 performance and overall throughput.

By letting WLM increase your buffer pool allocations 25%, based on presentations at the 2009 IBM Information on Demand conference, you give more memory to active or vital data. Unfortunately, IBM’s standard increase of 25% may not be effective or correct for your situation so you will need to test this recommendation. Increasing the buffer pool size usually leads to improved I/O rates. These improved I/O rates can dramatically drop CPU and improve overall I/O processing and DB2 performance.

Improving buffer pool sizes for increased I/O rates has been around since DB2 Version 1. Over the years, I have personally worked with clients and enlarged, reduced and optimized many systems’ buffer pools for better throughput. It is a good idea to enhance DB2 buffer pools and even though this enhancement is very basic, the concept is a good idea.

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