memory usage free -m | free column is Free + Cached + buffers
# free -mt total used free shared buffers cached Mem: 7974 7921 53 0 27 2107 -/+ buffers/cache: 5786 2187 Swap: 5945 923 5022 Total: 13920 8844 5075 You get a similar misleading result, but you get to see the actual server condition too. As you can see, the first free value is very low and that’s what is concerning you. However I want to draw your attention to the next line. That’s really where you need to watch. If you look at the buffers/cache line, you can see that used value is 5786mb and we have 2107mb in the free column. That free column is the Free + Cached + buffers (plus/minus rounding error of less than 2 Kbytes). That’s really the line that you need to watch. From that line we can tell that we have used 5.79gb out of the 7.97gb of total physical memory already used by programs. We can also see that we have 2.19gb of RAM that is in the cached pool that is available for usage. To look at how much memory each program is using, I use this line: # ps aux|head