As a rule, to solve problems of the server you need to know what happened to it before. Here, monitoring systems come to the rescue. Today there is a wide range of useful monitoring systems (and Nagios is regarded to be the most popular one). Among them Munin should be marked out.
Munin is convenient and easy-to-configure tool of server performance monitoring. It has a large number of useful plug-ins available right away after installing. Its extensible functionality allows to monitor virtually every server characteristic: load average, network, CPU loading, memory usage, postfix, exim4, mysql and many more. More →