I have Apache +Mysql+ PHP installed on 4G memory server which serve around 20000 visits per day. The following graph shows the memory utilization for one day. As you can see from the graph: the free memory is low (e.g 155 M) and the cached memory is high (e.g 2G). This server did not use the swap memory ever.
- do I need to increase the memory?
- Is it safe to have low free memory but high cached memory?
- How do I find which application using a lot of cache memory?
Thanks a lot for help.