system sizing

[Jan Meijer]

Hi,
I?m looking for whitepapers / articles / books which present a structured approach of sizing system hardware. How to interpret the tpc en spec scores, how to map these on a real life software product etc. Does anybody know where to find this kind of documentation?

[Tim Malnati]

Take a look at http://www.tpc.org and http://www.spec.org In particular, look at their FAQ sections. I'll quote one comment from TPC that says a lot:

"Q: How can I tell if one of the TPC benchmarks is relevant to my application and environment?

A: This is an extremely difficult question to answer as the range of customer application environments is almost infinite and benchmarks are necessarily abstract and simplified models of all those environments. For this reason, TPC benchmarks represent a good yardstick for comparing different systems rather than a precise tool for capacity planning for a given customer application environment. The best approach is to reach a deeper understanding of the benchmark and compare its model (user interaction, database design, database size, transaction complexity, processing requirements, storage/backup tests) with your own application environment. If there is a rough match, you probably have a useful and relevant tool for comparing different systems that may be installed in your environment."

The bottom line here is that machine sizing is more a knowledge of your specific application environment and how that relates to the variety of machine offerings available. The first source of information of this type is the vendor who wrote the software. They should have some clear idea of what you will require. The issue here is how reliable is the information you will receive from the vendor? They often can tend to undersize things if they believe thay are in serious competition with another vendor; they can tend to oversize if they believe there is no competition; or they may not be technically competent enough to give you a reliable answer (or don't want to). If this is a large purchase, I always request customer references and make the appropriate calls to all of them. No less than three; five or more is preferred. If this is an internally developed application, the only reliable method is to create a benchmark yourself that adequately tests it. Most machine vendors either have a facility to benchmark your application, or are willing to provide you with a loaner machine to do it yourself.

Maybe not the response you wanted to hear, but this is reality.