Description of problem:

The check_disk plugin (nagios-plugins-disk) contains a bug which was introduced in upstream 2.3.0 (check_disk: Add support for base-10 units kB, MB, GB, TB; rename base-2 units to KiB, MiB, GiB, TiB). 

The bug is reported upstream in https://github.com/nagios-plugins/nagios-plugins/issues/518 and was fixed in nagios-plugins 2.3.2 (check_disk: Change unit calculations to always use binary units for backward compatibility (#518)). 

However the EPEL package of nagios-plugins refers to version 2.3.3 but still contains this bug.

Unfortunately the incorrect UOM value in the performance data prevents data to be written into a graph database.


Version-Release number of selected component (if applicable):

Name        : nagios-plugins-disk
Arch        : x86_64
Version     : 2.3.3
Release     : 2.el7
Size        : 86 k
Repo        : installed
From repo   : epel
Summary     : Nagios Plugin - check_disk
URL         : https://www.nagios-plugins.org/
License     : GPLv2+
Description : Provides check_disk support for Nagios.


How reproducible:

Run the plugin and check the performance data output.

/usr/lib/nagios/plugins/check_disk -w 15% -c 5% -W 15% -K 5% -p /
DISK OK - free space: / 8640 MiB (76.21% inode=95%);| /=2696MiB;10171;11368;0;11967



Steps to Reproduce:
1. Run /usr/lib/nagios/plugins/check_disk -w 15% -c 5% -W 15% -K 5% -p /

Actual results:

DISK OK - free space: / 8640 MiB (76.21% inode=95%);| /=2696MiB;10171;11368;0;11967


Expected results:

DISK OK - free space: / 8640 MiB (76.21% inode=95%);| /=2696MB;10171;11368;0;11967

Note the difference between MiB and MB. Even the Nagios Plugin developer guidelines require the UOM as (K|M|G)B, not MiB.

https://nagios-plugins.org/doc/guidelines.html#AEN200


Additional info:

https://nagios-plugins.org/doc/guidelines.html#AEN200
https://github.com/nagios-plugins/nagios-plugins/issues/518

A workaround is to use additional parameter "-m" but the default output should already be working.