[Nagiosplug-help] check_disk over NRPE executing fine locally, but returns 'not mounted' error in nagios

[Eli Stair]

I'm beginning a project monitoring a large number of hosts & switches with
Nagios (500+ compute nodes, 20+ servers) and am having a problem with two
Linux servers in particular, both with the same problem.  It comes down to
the check_disk plugin apparently returning the wrong status when executed
by nrpe.  Other plugins run on these hosts over nrpe are working fine
concurrently with this failure.

When run locally it responds with the proper info, however if executed by
nrpe it fails and spits to the logs and back to Nagios an error about the
device not being mounted.  I'm running the same command as is listed in
nrpe.cfg, I've killed and restarted nrpe and nagios just to make sure
things are right, but cannot figure out where this issue is stemming from.

All suggestions and help appreciated, thanks all.

/eli

###Below are snips from logs on one host having the problem:
...
Oct 29 16:19:31 ff017 nrpe[5829]: Host is asking for command 'check_sda'
to be run...
Oct 29 16:19:31 ff017 nrpe[5829]: Running command:
/usr/local/nagios/libexec/check_disk -w 75 -c 50 -p /dev/sda1
Oct 29 16:19:31 ff017 nrpe[5829]: Command completed with return code 2 and
output: Disk "/dev/sda1" not mounted or nonexistant
Oct 29 16:19:31 ff017 nrpe[5829]: Return Code: 2, Output: Disk "/dev/sda1"
not mounted or nonexistant
...

####running the command specified in nrpe.cfg above results in:

ff017:/var/log # /usr/local/nagios/libexec/check_disk -w 75 -c 50 -p
/dev/sda1
DISK OK [600123520 kB (51%) free on /dev/sda1]

####However, in Nagios I get a service check failure with the following
reported:

Disk "/dev/sda1" not mounted or nonexistant


-- 
Eli Stair
University of Utah
Center for High Performance Computing
155 South 1452 East RM 405-17
SLC, UT 84112
Tel: 801-