[PLUG] How to umount NFS hung mouts

Felix Lee felix.1 at canids.net
Thu Aug 14 13:57:01 UTC 2003


"Steven A. Adams" <stevea at nwtechops.com>:
> Implicating the filesystem protocol because an application is not
> properly using that protocol? You have to admit, that's really
> stretching things.

The programmers were properly using the "unix filesystem
protocol" (open, read, write, etc).  The issue is that adding
"nfs behavior" to the "unix filesystem protocol" changes the
protocol in ways that programmers may not have originally
considered.  nfs implementations go to a _lot_ of trouble to try
to conform to the unix protocol, except for some unavoidable
problems like close(), but these guarantees apply to hard mounts,
not soft mounts.

Look, programming is sometimes like mathematics, and statements
like "this program works correctly" or "this program is secure"
are similar to mathematical proofs.  The proofs become invalid if
you change any of the axioms.  Using soft mounts instead of hard
mounts is like saying "ok, I'm changing '+' so that 2 + 2 = 0
when everyone in the room shouts 'fire!, but that's so rare that
everything should still work."  Logic systems just fall apart
when you make changes like that.  Every previously proven
statement becomes questionable.  You have to do new proofs, and I
don't know that anyone's done that for soft nfs mounts.  Someone
should go look.
--




More information about the PLUG mailing list