Nice. I would just add one comment. vmstat is very useful if you run VPS. It can be used to easily detect when your hosting provider is overselling the hardware

Nice. I would just add one comment. vmstat is very useful if you run VPS. It can be used to easily detect when your hosting provider is overselling the hardware and other users are killing the I/O (which happens to be the biggest bottleneck in VPS as CPU and RAM can be easily shared and sliced)