After physical design and SQL tuning, bufferpools are the greatest tuning opportunity for your system and applications.
Last year at IDUG ‘97, Intria/CIBC illustrated their projected CPU/cost saving at $1.3 Million Dollars over three years from I/O elimination, as well as reducing average transaction elapsed times by 20% for one system and 13% for a second system (presented at IDUG ‘97 by Patrick Morrison & Richard Gaunt).
The most important consideration for Buffer Pool tuning is the ability to predict the effect of changes – to avoid creating new or worse performance problems, or suffer an application outage while objects are stopped/restarted to move them into different pools.
Pool tuning is not mysticism or a guessing game, nor is DASD tuning. Tools exist to help you do it the right way and achieve a substantial payback.