“To monitor the memory usage of unix server, you can log in and run the ‘top’ command at the command line. Hit q to quit the program
On the Swap line, if the free value approaches zero, the system is seriously running out of RAM. Another symptom is the load average (on the top line) hits 5 or more. The load average is the number of processes ready and waiting to run over short/medium/long time spans.
If you see the load average creeping up and there is no real reason, run ‘service httpd restart’ and then we will have to tweak the settings some more.”
— master p