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From: jans@stalker.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: Really, redundant file servers
Message-ID: <8146@tekecs.TEK.COM>
Date: Tue, 10-Feb-87 11:58:52 EST
Article-I.D.: tekecs.8146
Posted: Tue Feb 10 11:58:52 1987
Date-Received: Fri, 13-Feb-87 06:28:09 EST
References: <2592@phri.UUCP> <12959@sun.uucp>
Sender: nobody@tekecs.TEK.COM
Reply-To: jans@stalker.UUCP (Jan Steinman)
Distribution: world
Organization: Tektronix, Inc., Wilsonville, OR
Lines: 19

In article <12959@sun.uucp> dss@sun.UUCP (Daniel Steinberg) writes:
>In article <2592@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
>>
>>	How hard would it be to incorporate a "shadow server" mode into
>>NFS?  Imagine 2 servers serving the same file system...
>
>In many ways it is simpler to have a physical disk shadow than a
>filesystem shadow...

Simpler, and MUCH more efficient.  The Tandem NonStop fault-tolerant
computers provide parallel writes, but split seeks on reads.  I.e.: One
disk is assigned cylinders 0-405, the other cylinders 406-811, reducing
the average seek time by a factor approching two.  The actual improvement
is tempered by accelerated seeks, out-of-area writes, and non-locality of
reference.

:::::: Artificial   Intelligence   Machines   ---   Smalltalk   Project ::::::
:::::: Jan Steinman		Box 1000, MS 60-405	(w)503/685-2956 ::::::
:::::: tektronix!tekecs!jans	Wilsonville, OR 97070	(h)503/657-7703 ::::::