Path: utzoo!utgpu!bnr-vpa!bnr-fos!tpc
From: tpc@bnr-fos.UUCP (Tom Chmara)
Newsgroups: comp.dcom.lans
Subject: Re: NFS vs RFS
Message-ID: <247@bnr-fos.UUCP>
Date: 17 Jan 89 14:38:06 GMT
References: <9018@cit-vax.Caltech.Edu> <7387@chinet.chi.il.us> <437@aurora.AthabascaU.CA> <340@moriaMoria.Sp.Unisys.Com>
Reply-To: tpc@bnr-fos.UUCP (Tom Chmara)
Organization: Bell-Northern Research, Ottawa, Canada
Lines: 45

In article <340@moriaMoria.Sp.Unisys.Com> tdh@moriaMoria.Sp.Unisys.Com (Thomas Hintz) writes:
>In article <437@aurora.AthabascaU.CA>, rwa@auvax.uucp (Ross Alexander) writes:
>> In article <7387@chinet.chi.il.us>, Leslie Mikesell writes:
>> > I've only used RFS but as I understand things RFS preserves the unix
>> > semantics to a greater extent than NFS.
>> 
>Sun sells NFS as a stateless remote file system protocol over a lightweight,
>unreliable transport (UDP).  File locking, mounting facilities are there too.
>
>AT&T sells everyone on a statefull protocol that implements full semantics
							     ^^^^^^^^^^^^^^

>running over a reliable transport (TCP).
>
>The RFS TCP transport implementation incurs more overhead on every packet
>to ensure reliability, plus RFS incurs a lot of overhead in the way it
>implements the UNIX semantics and crash recovery.
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>
>Personal conclusions:  NFS performs better in reliable LANs where tight UNIX
>filesystem semantics aren't required, but RFS may perform better in unreliable
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


I am a bit concerned about these observations.  I understand that being
stateless, implementing some of the behaviour of a standard UNIX FS is
a problem; however, I do not see them as impossible obstacles.  As I under-
stand it, many of the "file locking" semantics, etc. are performed by
ancilliary facilities (the "Network Lock Manager").  What UNIX semantics
(aside from mandatory file locking, an admitted failing in NFS) are
missing or compromised?  This is a particular concern for diskless
environments -- and we're seeing more and more of those.  Does a diskless
environment (using NFS exclusively, as with SunOS 4.0.[0-1]) exhibit
SVID-compliant behaviour (minus file locking)?  If not, what am I giving
up?  Are application programs in trouble in this environment?

Thanks for taking the time...I will summarize responses if need warrants.


-- 
I am sole owner of the above opinions. Licensing inquiries welcome.
------------------------------------------------------------------------
Tom Chmara			UUCP:  ..utgpu!bnr-vpa!bnr-fos!tpc
BNR Ltd.  			BITNET: TPC@BNR.CA