Brendan Gregg's [linux perf](http://www.brendangregg.com/linuxperf.html http://www.brendangregg.com/linuxperf.html) posts. They a great reference for linux too

Brendan Gregg's [linux perf](http://www.brendangregg.com/linuxperf.html http://www.brendangregg.com/linuxperf.html) posts. They a great reference for linux tools and how to use them. They are also a great guide to deductive reasoning when spelunking through a system to find issues.