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?
i suggest you rather monitor swap usage. check out check_swap plugin - it comes by default [at least in debian].
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...
WARNING - 9.9% (406520 kB) free!|TOTAL=4113824KB;;;; USED=3707304KB;;;; FREE=406520KB;;;; CACHES=816947KB;;;;
So, the configuration steps are simple: