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From: zrm@mit-eddie.UUCP
Newsgroups: comp.sys.mac
Subject: Re: Faster networks
Message-ID: <5777@eddie.MIT.EDU>
Date: Mon, 11-May-87 19:15:03 EDT
Article-I.D.: eddie.5777
Posted: Mon May 11 19:15:03 1987
Date-Received: Wed, 13-May-87 07:23:26 EDT
References: <347@aucs.UUCP>
Reply-To: zrm@eddie.MIT.EDU (Zigurd R. Mednieks)
Distribution: na
Organization: MIT EE/CS Computer Facility, Cambridge, MA
Lines: 71
Keywords: Networks, Appletalk, Ethernet, SCSI

In article <347@aucs.UUCP> paul@aucs.UUCP (Paul Steele) writes:
>I would like to here from people who has tried other approaches to
>networking Machintoshes besides the slow Appletalk method.  We will
>be installing a lab of Macintoshes and dread the problems that "slowtalk"
>will cause our users.  We want 15-20 stations, with hopes for future...

A common problem. Every one of my consulting clients with more that 10
Machintoshes has asked me the same question.

1) Appletalk performs about as well as a floppy disk, so it is
adequate for most file-serving operations, but not those involving big
databases. It is certainly fast enough for E-mail, file copying, and
most transaction processing. A combination of Appletalk and an
Ethernet backbone would expand the area the network could cover and
keep the sub-nets from being overloaded.

2) Networks that cost more than $200-$300 per node are not cost
competitive with local hard disks, which are down to $600 per 20Mb.
You won't be able to beat that with a combination of faster networking
and file servers with large, presumably lower cost per Mb, disks.

	Hypothetical
	Ethernet
	-----------
	Adapter		$200/node x 50 nodes		$10,000
	Transciever	$150/node x 50 nodes		$ 7,500
	Cabling		$100/node x 50 nodes		$ 5,000
	500Mb disk server x 2 = 20Mb/node		$20,000
------------------------------------------------------------------------
							$42,500

	AppleTalk
	----------
	Isolation transformer $40/node x 50 nodes	$ 2,000
	Cabling		$20/node x 50 nodes		$ 1,000
	20Mb Hard Disk	$600/node x 50 nodes		$30,000
------------------------------------------------------------------------
							$33,000

3) Items 1) and 2) probably explain why there are no Ethernet systems
for the Macintosh Plus or SE. There will probably be more than one
Ethernet adapter for the Macintosh II, for which the economics of mass
storge are very different.

NOTE: My assumptions about the Ethernet are a bit iffy -- I have never
seen an Ethernet file server serve 25 machines and do it well. File
serving only works when big disks are part of the equation anyway, for
performance reasons or because you really need a 500Mb volume.
Otherwise small cheap disks are it. The comparison also avoids the
robustness issue: what happens when one of the few big servers goes down?

The recipe for a university's Macintosh net? Since they get
university pricing, the Macintosh SE with the 20Mb hard disk is the
right machine. Use Appletalk, but not the Appletalk cabling. Use
Faralon Phone Net cabling. Use Kinetics Fastpath Appletalk-to-Ethernet
adapters to build an Ethernet backbone. This will yield, by far, the best
performance. If cost is a big issue, the Ethernet backbone can be
omitted until the network grows beyond 2 subnets with 20 machines
each. If you need to distribute course materials, put an 80Mb disk on
one node.

I read in a trade rag that Apple "does not believe in diskless nodes."
or something to that effect. The economics of small cheap disks is
probably the reason why.

-Zigurd
---------------------------------------------------------------------------
Zigurd Mednieks
MURSU Corporation
P.O. Box 1894
Cambridge, MA 02138					(617) 522-9035
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