Why server is so slow? - Use "The USE Method" !

I'm excited!
I've just found fabulous posts in DTrace blog -

1. The USE Method - http://dtrace.org/blogs/brendan/2012/02/29/the-use-method/
2. The USE Method: Solaris checklist - http://dtrace.org/blogs/brendan/2012/03/01/the-use-method-solaris-performance-checklist/
3. The USE Method: Linux checklist - http://dtrace.org/blogs/brendan/2012/03/07/the-use-method-linux-performance-checklist/
At glance - it's about method of checking system performance problem - USE (utilization, saturation, errors) method. In case of server system we have different resources - CPU, memory, storage, network etc.
For each resource we check

• utilization: the average time that the resource was busy servicing work
• saturation: the degree to which the resource has extra work which it can’t service, often queued
• errors: the count of error events 

Usually we need to check for errors first, then utilization and saturation after this. But it's really short explanation - I beg you to check original posts. :) In next two posts Brendan provides recomendations with lists of commands for Solaris and Linux for using USE method.
And USE method is usable even without dtrace - Linux do not have native dtrace, and authors of original Dtrace blames current versions of Linux dtrace very hard. :)