Okay, so I’ve got NRPE running. Just now got it worked out, as a matter of fact…or at least, I think I do. Nagios is checking disk space on the root partition of a remote host. I’ve run the check_nrpe command from my Nagios box and ran the check_disk command locally, but the results I’m getting aren’t exactly the same. Percentage wise, they both show 85% free disk space…but number-wise, they’re about 6 MB different. Running the check_disk plugin locally on the remote host shows 6 MB more disk space than do the results of running the check_nrpe command on my Nagios machine. Any ideas as to what’s up? I thought NRPE was supposed to just return to Nagios the results of its local check.
check for root reserved space, or try the usual disk conversion 1024/1000 
Luca
I figured out why…it was because I was monitoring the disk space of a MAIL SERVER!!! It’s pretty busy; we get lots of spam and whatnot, so the difference was just in the amount of information that had yet to be downloaded locally on the employee desktops.