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

Wed Feb 2 23:49:27 UTC 2011
Dr. Ed Morbius <dredmorbius at gmail.com>

on 05:58 Thu 03 Feb, mcclnx mcc (mcclnx at yahoo.com.tw) 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. 
> 
> Since server have 128 GB RAM and only 1 application.  I really don't
> belive that.  Does there has some way can check memory utilitation ?

Make sure your tool is reporting utilization less cache.

As others have noted, the "-/+ buffers/cache" line in "free" output is
what you're looking for.

    http://www.linuxatemyram.com/


If you've got sar (sysstat) installed and activated (read the manpage
and /usr/share/doc/sysstat* materials if not), numerous system resource
usages are logged every ten minutes.  For memory usage: 'sar -r':

12:00:01 AM kbmemfree kbmemused  %memused kbbuffers  kbcached kbswpfree kbswpused  %swpused  kbswpcad
12:10:01 AM  45877732   3573788      7.23    208792   1948316   2097144         0      0.00         0
12:20:01 AM  45875572   3575948      7.23    208792   1948336   2097144         0      0.00         0
12:30:01 AM  45877120   3574400      7.23    208796   1948352   2097144         0      0.00         0
12:40:01 AM  45878352   3573168      7.23    208796   1948368   2097144         0      0.00         0
12:50:01 AM  45876080   3575440      7.23    208800   1948384   2097144         0      0.00         0
01:00:01 AM  45877244   3574276      7.23    208800   1948408   2097144         0      0.00         0

There are tools (NOT currently in CentOS) to graph/visualize these
outputs as well.


If you want per-process accounting, you can get that as well, but it'll
cost you some performance overhead and a lot of set-up.

-- 
Dr. Ed Morbius
Chief Scientist
Krell Power Systems Unlimited