Good resource for what to look for on Munin graphs?

Question

I have installed Munin to provide some insight into server performance for a VPS server with some small rails and Sinatra applications. Is there a good resource for reading up on what to look for on the graphs Munin provides. Or a good resource on getting more details on specific measures (Fork rate, Swap in/out) - what they are telling me, what are signals that need to be looked into...

Mainly I am trying to learn about what measures I should pay attention to on the server side as I try to work with some small ruby application for fun.

Answer 1

When you install munin you get a bunch of default plugins which graph system metrics. To begin with, it would be a good idea to keep an eye on load-avg, cpu%, memory, swap in/out.

If you're not sure exactly how munin is calculating a specific metric, you can try reading the source code for the plugin script. Usually system metrics are obtained from the /proc filesystem. On a debian/ubuntu box, munin plugin scripts are installed (via a symlink) under /etc/munin/plugins. You can install your custom plugins by simply dropping them somewhere and symlinking to them from /etc/munin/plugins.