First of all let me start off saying that I learned a lot of Capacity Planning from two people. Jozo Dujmovic, and John Allspaw-who by the way is coming out with a book.
Capacity != Performance. You may have the capacity to do a bubble sort but a bubble sort is still a bubble sort.
Really to Scale you need to know when your application will break. I have a tool set to help determine what application is producing what SQL and use that to figure out which SQL is producing the most load on the system. Some common tricks I do is put the execution path automatically as a SQL comment, then sample the FULL Processlist to build a graph on what application, function, SQL pattern is the top load.
On top of that I use [Read more...]