Linux Ram Usage Monitor

by Aug 9, 2013

Hi, My RAM usage monitors keep going to 99.5% as Linux uses any spare from the 32 GB of RAM on my servers for the buffer cache

-bash-3.2$ free

total used free shared buffers cached

Mem: 32945612 32767728 177884 0 142792 28493848

-/+ buffers/cache: 4131088 28814524

Swap: 2096472 101476 1994996

In fact mySQL, the only thing running on this server, is only using 10.3% of the memory

-bash-3.2$ top

Mem: 32945612k total, 32778648k used, 166964k free, 143656k buffers

Swap: 2096472k total, 101476k used, 1994996k free, 28501952k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

15112 mysql 15 0 20.2g 3.2g 5704 S 94.2 10.3 43:27.69 mysqld

So I think the memory usage is low and there is lots of RAM available to apps as required to be released by Linux from the buffer cache.

Linux seems to be using the 90% available memory well as we are disk I/O intensive (to a RAID 10 array 2+2 and 1+1 15k disks)

So why does MoNyog keep warning me that this memory is low and that thrashing may occur?

Thanks for the help, all my other monitors are green 🙂