The overall performance of Db2 z/OS depends highly on its I/O performance, which is in turn mainly influenced by the behavior of the buffer pools. Whereas SQL tuning efforts might be labor-intensive and costly, the Buffer Pool tuning with the aide of tuning tools is something that can easily be done by system DBA’s. Interaction with application development is rarely necessary and tuning success is achieved really fast. Very often only small changes lead to significant improvements.
The main purpose of the bufferpools is to save I/O, hence to save CPU work. Performance degrades when we fail to keep the right pages as long as possible in the pools. The right pages are those that are accessed again and again. What can be a relatively simple task can turn out to be a huge non-ending task when you have to work with inappropriate tools. Don’t be left to the fate of Greek mythological King Sisyphus, buffer pool tools are a requirement today.