> Hmmm. The "invalid argument" message makes it sound like it just isn't 
> parsing the line correctly. Which made me think that it wasn't passed on 
> to umount_nfs.
> 
> How about "umount -t nfs /flam/stuffy" (or flam:/stuffy) ?
> I'm sortof guessing here, but the error message sortof indicates that it 
> don't even try to unmount, since it cannot correctly parse what you want.
> 
> But yes, you're right. umount can take either information, and extracts 
> the other stuff from the fstab. Hmmm. What happens if you do
> "umount flam:/stuffy /flam/stuffy" ?

Nope, nothing works:

# umount -t nfs /flam/stuffy
umount: /flam/stuffy: Invalid argument
# umount -t nfs flam:/stuffy
umount: /flam/stuffy: Invalid argument
# umount flam:/stuffy /flam/stuffy
umount: /flam/stuffy: Invalid argument
umount: /flam/stuffy: Invalid argument

At the same time it is no problem to umount other nfs volumes:

# umount -t nfs flam:/volatile
#