Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mcnc!ecsvax!dukeac!bet
From: bet@dukeac.UUCP (Bennett Todd)
Newsgroups: comp.emacs
Subject: Re: Does GNU emacs ever use shared libraries?
Message-ID: <1411@dukeac.UUCP>
Date: 17 May 89 20:42:44 GMT
References: <152@talarian.UUCP> <PINKAS.89May14180259@hobbit.intel.com> <39999@bbn.COM> <11471@bloom-beacon.MIT.EDU>
Reply-To: bet@dukeac.UUCP (Bennett Todd)
Organization: Radiology, Duke Med. Center, Durham, NC
Lines: 34

In article <11471@bloom-beacon.MIT.EDU> jik@athena.mit.edu (Jonathan I. Kamens)
writes an excellent explanation of NFS's stateless nature, and its
implications for removing binaries of currently-running programs and suchlike.

I would add that an alternative network distributed filesystem is available
for some systems (not nearly as many as NFS) called RFS. Designed by AT&T, it
differs from NFS in several important respects. It sincerely attempts to
maintain the semantics of unlink removing the name, but not freeing the inode
and data blocks until the last open handle is closed. This makes it more true
to UNIX filesystem semantics; it also forces it to be stateful, and is reason
enough for me to hope I never have to administrate such a network. Sun's NFS
is wonderful to support, since the surprises are reasonably obscure and
infrequent, and the common case of systems going down and whatnot is handled
extremely well and robustly. We can reboot our main server anytime, and the
worst anyone sees is a minute or so of lockup. Reboot an RFS server and you
better reboot every client while you are about it. Another important feature
of RFS is support for device special files; the resulting major/minor device
numbers are correctly processed by the server, rather than being interpreted
relative to the client the way NFS does. On the other hand, by having such
complete detailed specification of UNIX filesystem semantics, efforts to
support RFS from non-UNIX OS platforms are at a great disadvantage relative to
NFS, which has OS independence as an important goal.

To sum up, I don't mean to beat up on RFS. Given a reliable LAN with reliable
homogenous servers and clients, it delivers a much higher level of
functionality, and truly distributes the UNIX filesystem transparently. On the
other hand, hetrogenous networks with unreliable servers see better service
from NFS.

Obviously, these are my opinions only; I would love to be taught why I am
wrong, if anybody would care to enlighten me. But please be nice:-).

-Bennett
bet@orion.mc.duke.edu