How to monitor memory usage of linux server using nagios

Question

Just installed nagios on a central machine and nrpe on 10 remote linux machines and just started monitoring them. It works great. I can get cpu load, current users, processes, mysql, etc. I can't find a way to monitor memory usage using the core plugins. What am I missing? Do I need an external plugin to do this?

Answer 1

i suggest you rather monitor swap usage. check out check_swap plugin - it comes by default [at least in debian].

Answer 2

yes, i do thought why they didnt include a plugin which will check the memory, when they have included check_swap and check_disk... ok, something wrong... but the check_memory plugin is available from the exchange.nagios.org http://exchange.nagios.org/directory/Plugins/Operating-Systems/Solaris/check_mem-2Epl/details

this one works pretty nice.. its a perl script, so not even an installation needed... this is the link http://sysadminsjourney.com/content/2009/06/04/new-and-improved-checkmempl-nagios-plugin/ from the above plugin page...simple and good documentation...

$ /usr/local/nagios/libexec/check_mem.pl -w 10 -c 5 -f 

WARNING - 9.9% (406520 kB) free!|TOTAL=4113824KB;;;; USED=3707304KB;;;; FREE=406520KB;;;; CACHES=816947KB;;;;

So, the configuration steps are simple:

• Copy the perl script and write it as "check_memory" (or check_mem or a suitable name for you) in the same directory as where you have the check_disk, check_load etc
  
  • important to change the execute permissions to that check_memory similar to the other check_plugins(i mean, the execute permission should be given to the nagios user. in our dev environment i gave 755, please verify whether you need 754 or 755)
  • update the remote client nrpe.cfg config file with the command[check_memory]=/usr/lib64/nagios/plugins/check_memory -u -w 8% -c 90%