[CentOS] centos 5.5 check memoray usage too high???

[Stephen Harris]

On Thu, Feb 03, 2011 at 05:58:19AM +0800, mcclnx mcc wrote:
> We have DELL R900 server with 128GB RAM (CENTOS 5.5)in it.  This server only have one application running and few people use it.
> 
> Every week I ata least get one or two messages from monitor tool mail to me say:
> 
> Message=Memory Utilization is 92.02%, crossed warning (80) or critical (90) threshold. 

It sounds like your monitor tool is probably misconfigured and is looking
at "free memory", which is a very low value 'cos unused memory is used as
disk cache.  

eg
% free -m
             total       used       free     shared    buffers     cached
Mem:          3987       3551        435          0        330       2987
-/+ buffers/cache:        233       3753
Swap:         2047          0       2047

This machine has 435M free, out of almost 4G.  Except not really; it's got 
3753M available for programs to use and is only using 233M of memory for
"real" stuff!

-- 

rgds
Stephen