[CentOS] free memory listing

Tue Dec 18 07:44:11 UTC 2012
John R Pierce <pierce at hogranch.com>

On 12/17/2012 11:19 PM, AshikAli.m wrote:
> [root at machine1 ~]# free -m
>               total       used       free     shared    buffers     cached
> Mem:    32183       1309      30873          0        290        485
> -/+ buffers/cache:   533      31649
> Swap:        51199          0      51199

so you have about 32gb total physical memory.  1.3gb of that is 'used' 
but of that 290MB is buffers and 485MB is cache, so really only 533MB 
(the 2nd line) is in use by software, and 31649MB is available (which is 
the 30873 free on the 1st line, plus the 290 buffers plus the 485 
cached, as all that is considered 'discardable' [*].

you also have 51199MB of swapfile, entirely unused.

this looks to me like a system that was just booted, and hasn't done much.

[*] under heavy loads, like a buay large scale database server, this sum 
isn't exactly true, some of the buffer memory is 'dirty' so not 
considered as free without first flushing it to disk...