Hi, We discovered some quite strange result from the check_mem plugin :
root@server:~# /usr/lib/nagios/plugins/check_mem --version check_mem v$Revision: 1.8 $ (monitoring-plugins 2.1.2) The Monitoring Plugins come with ABSOLUTELY NO WARRANTY. You may redistribute copies of the plugins under the terms of the GNU General Public License. For more information about these matters, see the file named COPYING. It says that no memory is used and some swap is. By looking the output from free, we read completely different values : root@server:~# /usr/lib/nagios/plugins/check_mem -w 85,25 -c 92,50 <b>WARNING: Memory Usage (W> 85, C> 92): 0% <br>Swap Usage (W> 25, C> 50): 27%</b>|MemUsed=0%;85;92 SwapUsed=27%;25;50 root@server:~# free -k total used free shared buff/cache available Mem: 2039560 804156 435688 21404 799716 1010344 Swap: 975868 0 975868 The host is a VM (VMware) running Ubuntu 16.04 server. Any idea on this inconsistency? Regards, Samuel Bancal -- Samuel Bancal ENAC-IT EPFL