How much RAM am I using on my server?

[ntbgl]

I have a unix dedicated server for my site, and I just found out today that I can pay a one time fee to add more RAM to my server.

I'm wondering how I can tell how much of my current RAM the server is using, and if I would benefit from increasing this amount, and if so, how much ram for what kind of benefit.

I'm sure more is better, but how do I know how much is good, and what would be overkill.

Thanks

[J_RaD]

you need to get a benchmark on memory usage to tell.

[lammert]

I have installed the open source package Munin on my servers. It produces graphs of all kind of resource usage, including memory usage. The data is sampled every five minutes which gives you a good view of memory usage during the day. If you see a low amount of unused memory or available cache, it is time to upgrade your memory.

Some of this information can also be obtained with the program top, which is installed by default in most distributions.