Re: Need information on NFS


Bob Braden (braden@isi.edu)
Fri, 19 Dec 86 10:30:44 PST


        Sun's NFS is NOT a good Unix Networked Filesystem. They broke
        some Unix semantics in the name of generality to the non-unix world.
        Sun claims it to be a non-unix specific design.

Are we to read "not good" as "bad"? If not, what do you mean by this
complaint? If so, why should we standardize a protocol which is bad for
an important class of hosts?

        What do you see as the major problems? "Considerable work" doesn't sound
        right.

The problem most people have cited is NFS' authentication/permission
model, which is not only Unix-oriented but also perhaps inadequate. This
is a hard and important issue. In fact, it has been pointed out that the
assumption of globally-unique uid's and gid's is invalid in many sites even
among Unix systems.

Another problem is in the remote mount protocol. SUN treats it as separate,
yet it seems that its functions ought to be included in any network file
system standard.

Another set of issues has to do with convincing ourselves that the
NFS primitives have sufficient generality to provide useful service with
the other file systems in the world besides Unix. That probably means
generalizing the existing primitives and adding a few more. It also
means providing defined hooks for extensibility.

Finally, there is the issue of underlying layers. NFS assumes two other
protocols, XDR and RPC. It seems desirable to define NFS independently
of the lower layers, so different choices could be made in the future
for these protocols (after all, that is what layering is really for).
RPC, in particular, is highly doubtful in its present form as an Internet
standard, as its transport-protocol mechanism seems deficient.

        It seems to run with MS-DOS and VMS as far as I know. So, it's not
        too Unix-specific.

More information about the generality and completeness of these implementations
would be interesting and useful. Could I do a remote mount from my SUN to
our VMS machine, for example, and access any VMS file? Can the VMS machine
get at any Unix file (subject to permissions)? How do permissions work?

Finally, I don't know how much time you have spent on protocol committees,
but every one of the existing Internet protocols represents several manyears
(or more) of concentrated effort, spread out over 2-5 years.

Bob Braden



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