hardware sizing vs capacity planning

Question

Folks, Is hardware sizing and capacity planning same? I have seen these terms being used together and google does not return any results that help me understand the difference.

Would appreciate any explanations.

regards, avajurug

Answer 1

There is a very accurate difference as explained by Joel in Capacity Planning, H/W Sizing:

"[...] decide whether you need to do capacity planning or hardware sizing, you can't do both, at least not at the same time. In capacity planning the software and hardware are constant while the workload varies (ie, given a particular system, how much work can it do?). In hardware sizing the software and workload are constant while the hardware varies (ie, given a particular amount of work, what's the least-costly system that can handle the workoad in the specified performance constraints?)."

Answer 2

I would call hardware sizing the initial step. After you sized your hardware, you hope that it will be able to meet the demands for a period X.

Capacity planing is rather an ongoing process, by which you make sure that the system will be able to meet the loads of the changing demands. You decide when you want to add more power to the enviroment (before or after the limits are reached)