Checks GlusterFS health on the server. Tests include:
- daemons running
- number of bricks online
- disk space
- healing status

Needs some sudo rights:

Defaults:nagios !requiretty 
nagios ALL=(root) NOPASSWD:/usr/sbin/gluster volume status * detail,/usr/sbin/gluster volume heal * info

USAGE: 
  check_glusterfs -v VOLUME -n BRICKS [-w GB -c GB]
  -n BRICKS: number of bricks
  -w and -c values in GB
           