The number of IOs/second:

Imagine you have a large database say many megabytes, ( just like a movie file )

What these values tell you is the number of RANDOM reads within that file that can be done per second.

Standard ata drives, only manage around 100 random reads per second.

So your fast computer is stalled by the speed of your disc drive - if you are doing things like serving lots of webpages - to lots of different users - who all need access to different pages.

This is similiar to the way catalyst works.