Problem:

At the time of writing, the 3rd party check_nt plugin, distributed with OP5, does not have an option to use absolute units but only percentages.

Possible solution(s):

The only way to achieve this using check_nt would be to create a wrapper script. An example can be seen here on serverfault.com

A simpler solution would be to use the check_nrpe plugin instead.

e.g. on the command line.

# ./check_nrpe -2 -S TLSv1.2+ -H 192.168.10.182 -c CheckDriveSize -a ShowAll=long "c:" MaxWarn=20G MaxCrit=30G
WARNING warning(c:: Total: 41.666GB - Used: 29.519GB (71%) - Free: 12.147GB (29%))|'c: used'=29.51916GB;20;30;0;41.66601 'c: used %'=71%;48;72;0;100

and in OP5 Monitor.

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