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From: liam@cs.qmw.ac.uk (William Roberts)
Newsgroups: comp.protocols.nfs
Subject: Re: NeFS protocol
Message-ID: <2284@sequent.cs.qmw.ac.uk>
Date: 29 May 90 09:06:46 GMT
References: <1990May24.034258.13625@Neon.Stanford.EDU> <3378@auspex.auspex.com> <1990May24.205149.6065@Neon.Stanford.EDU> <3385@auspex.auspex.com> <1990May25.234950.1465@Neon.Stanford.EDU> <265DFAD2.5818@intercon.com>
Organization: Computer Science Dept, QMW, University of London, UK.
Lines: 52

In <265DFAD2.5818@intercon.com> amanda@mermaid.intercon.com (Amanda Walker) writes:

>Let me take a presently hypothetical example: a file service client for
>my favorite machine, the Apple Macintosh.  The biggest problem with doing
>this under NFS is that, despite a reasonable correspondence between the file
>systems themselves, the *operations* performable on a file system vary quite
>a bit between the Mac OS and NFS, thus requiring a ridiculous amount of either
>network traffic or client-side caching in order to get acceptable performance.
>With NeFS, the client can blort over some code that tells the server how
>to implement those operations that the client is going to want to invoke.

>Flexibility wins.  This is probably even more true for file service than
>for display service...


The NeFS spec is quite clearly written as a slight
generalisation over supporting a couple of slightly non-UNIX
file systems. It doesn't go anywhere near supporting
significantly different systems such as the Macintosh ("You
mean each file has two parts, plus comments?") even though the
polymorphic nature of PostScript would make it easy to allow
things like arrays or dictionaries of filehandles rather than
just single ones to be returned from open (for example).

Flexibility is good, but NeFS seems to me to be all wrong. It
dismisses the low-level network stuff with some hand waving,
and it just feels like an insane way to go about something
which needs to provide very high performance.

I loved PostScript and was very fond of NeWS until it needed
bigger machinery that I have available: NeFS just doesn't gell
at all.

I suggest we forget NeFS immediately and look at some real work
addressing real problems: anyone who hasn't read the Coda paper
should look out a copy

        Coda: A Highly Available File System for
              a Distributed Environment

        M. Satyanarayanan, J.J. Kistler et al
        IEEE Transactions on Computers, 39(4), 447-459,
        April 1990

Did anyone notice how little connection there was between the
list of "problems with NFS" and the proposed solution?
-- 

William Roberts                 ARPA: liam@cs.qmw.ac.uk
Queen Mary & Westfield College  UUCP: liam@qmw-cs.UUCP
Mile End Road                   AppleLink: UK0087
LONDON, E1 4NS, UK              Tel:  071-975 5250 (Fax: 081-980 6533)