Newsgroups: comp.protocols.nfs
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!bloom-beacon!vaxeline.ftp.com!backman
From: backman@vaxeline.ftp.com (Larry Backman)
Subject: Re: Symlink locking considered useless over NFS
Message-ID: <1991Apr23.113549.3605@vaxeline.ftp.com>
Organization: FTP Software, Inc., Wakefield, MA
References: <280EE8A1.30D@tct.com> <thurlow.672335997@convex.convex.com> <98765@sgi.sgi.com>
Date: Tue, 23 Apr 1991 11:35:49 GMT

In article <98765@sgi.sgi.com> vjs@rhyolite.wpd.sgi.com (Vernon Schryver) writes:
>
>NFS over TCP seems good if you're trying to get over a very slow or very
>lossy link.  NFS/TCP can't scale a fraction as far as NFS/UCP, despite
>statements to the contrary in that other, unnamed reference.  NFS/TCP seems
>a generally unlikely choice.
>
>I write this as someone who argued hard in the old NCF-NCS-NCA battles for
>optional connection oriented transport for remote procedures (i.e. NCS over
>TCP).  At Silicon Graphics, we care about remote procedures over TCP,
>because our graphics look like function calls, and we need performance
>several orders of magnitude faster than common remote procedure calls.
>(by cheating, we get enough of what we need).
>
>It seems straight forward to modify the Sun VAX reference code to use TCP
>handles, should anyone want to do it.


We at FTP Software would *love* to see some TCP NFS server's.  Our 
experience has convinced us that NFS/UDP is great for Sun's running
on a single local net without routers.  Once you start throwing 
complex networks into the equation with multiple router's between
you and your file system things can break down with UDP & the fragmentation/
reassembly issues.

Secondly; even on an local net, a fast server sending an 8K Read
response at a PC with an older network card (3c503, WD8003) can
throw stuff at the PC faster than the card can take it off the wire.
This is obviously fixable by doing smaller read's, however that is
going to affect overall throughput.

NFS/TCP solves both of those problems; the filing protocol (NFS)
can keep its large blcok size (8K), and let the TCP protocol
worry about how to get it through routers'; retransmit backoff's
and the like.

Of course, the TCP agument works only if your server's TCP can
put many megabits/sec. on the wire; most of the TCP's we've 
dealtwith lately seem to be more than capable of doing 3-4 Meg/Sec.


				Larry Backman
				backman@ftp.com