-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 22/08/08 10:46 AM, Edwin Zoeller wrote: > We have recently installed Redhat AS4 throughout our network. I have > installed various plugins from the Nagios Exchange site for Linux and > all seems to be well, except for the check_ram command. I am running > this on various servers with different configurations and all are giving > the same results. Here is what I have on one of the servers: > > check_ram -n -w 20MB -c 10MB ( the system has 8GB installed), results > display 30MB free (am I doing this right?) > > Other admins here are disputing the results and claim that Linux buffers > all the memory and gives what it needs. I don't know for fact it this is > true. I have also run top, free and ps -eo checking on memory size, all > give back the same results as the Nagios plugin. Is this plugin with the > option chosen giving real memory results or bogus results. > > My question, in desperation, can anyone explain in very simple terms how > Linux memory works? Also how are you monitoring memory, using what > command and how it is configured etc.
All unused memory gets buffered/cached eventually if your server is doing I/0. I've seen very stable servers with 32GB get down to only a few MBs free, but the picture is much better if you account the buffered/cached memory which for most of it can be freed anytime if needed. For that reason you should add the buffer/cache memory to the total (i.e. the "-/+ buffers/cache:" line of the "free" command). My check_memory script does that. it's written in Perl and uses the Nagios::Plugin Perl module (available on CPAN). http://www.nagiosexchange.org/cgi-bin/page.cgi?g=1433.html;d=1 - -- Thomas -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIr7bd6dZ+Kt5BchYRAqc2AJ9nJDwHfzVvSpXLpgzvmJ7NPygDhgCg1h28 1qpRXPn4Bx6/Oe09eHmnCOM= =CtE8 -----END PGP SIGNATURE----- ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Nagios-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nagios-users ::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. ::: Messages without supporting info will risk being sent to /dev/null
