When dealing with server-performance, monitoring peaks is important to understand under which circumstances performance-issues arise. Monitoring can be done by using plain tools like top and iostat, but now there also is GraphDat. Now monitoring server-resources is just a cool thing to do.
GraphDat offers a NodeJS based webapplication that can be fed with data from your server ... in real-time. After installing the agent on your server (you'll need root-access for that), the logging begins. Every second, data are sent from your server to the GraphDat server - CPU usage, memory usage, disc activitiy - which is then nicely displayed in a graph.
The GraphDat startup plan is free for 1 server. When analysing your own server, this is awesome already. If you need to monitor additional servers, they offer a $10 package for every server you add. Before to used to limit the data retention for the free account. Now it is completely free if you have only 1 server to monitor. Fantastic.
We think this is a great tool - hope you share the feeling!