Nagios Support Forum

is this correct?

total - free = 8193052 - 6360556 = 1832496 # with "-m"
total - free - cached = 8193052 - 6360556 - 856036 = 976460 # without "-m"

if we are calculating (total)-(free)-(cache), then it should be equal to the "used" memory shown by the free command?

please correct me if i am wrong here

The output of the second command would never match the output of the free command... In the free command both, the cached memory AND the buffers are subtracted... On the other hand, the plugin subtracts ONLY the cached memory, but NOT the buffers...

-/+ buffers/cache: 791108 7401944

Other words, instead of this:

total - free - cached = 8193052 - 6360556 - 856036 = 976460 # without "-m"

you would have this:

total - free - cached - buffers = 8193052 - 6360556 - 856036 - 185352 = 791108 # without "-m"