Hi,
you could trick the system. Just put following script in your check_mk agent local dir:
#!/bin/bash
if type waitmax >/dev/null 2>&1
then
OUT=$(waitmax -s 9 2 df -PTk | egrep ' nfs ')
[ x"$OUT" == x ] && exit
echo '<<<df>>>'
echo "${OUT}" | sed 's/ nfs / NFS /g'
fi
ttr