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Date:      Tue, 14 Dec 1999 18:53:55 +0000 (GMT)
From:      Terry Lambert <tlambert@primenet.com>
To:        brett@lariat.org (Brett Glass)
Cc:        tlambert@primenet.com, dscheidt@enteract.com, noslenj@swbell.net, chat@FreeBSD.ORG
Subject:   Re: dual 400 -> dual 600 worth it?
Message-ID:  <199912141853.LAA19833@usr02.primenet.com>
In-Reply-To: <4.2.0.58.19991213200556.0473c1e0@localhost> from "Brett Glass" at Dec 13, 99 08:33:45 pm

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> >I will let you in on a "secret": SCSI drives cost more because
> >that's what the market will bear, based on their performance
> >characteristics relative to IDE.
> 
> Unfortunately, I don't believe that the price/performance
> ratio of UltraSCSI is anywhere near that of Ultra-66 ATAPI.

Who said anything about that?  The market will bear higher
prices from SCSI, so SCSI costs more.


> >They cost the same to manufacture; it doesn't matter what mask
> >you use to burn your 1 square inch ASIC.
> 
> Which is the problem. You're being charged a premium for hardware
> that's very similar, due to lower volume. And SCSI has higher command 
> latency than IDE. SCSI drives usually make up for this with tagged 
> command queueing, hidden elevator seeking, and larger on-drive 
> caches. Sometimes this is a clear win, but sometimes it is not.

Sorry, but Bzzzt.  SCSI is actually cheaper in Europe than the
US.  It is a function of market pressures.  I can put you in
contact with the IBM Santa Teresa (disk drive manufacturing)
people if you need me to...


> The ideal thing would be a hybrid: a drive which supported the
> full SCSI command repertoire but didn't have the overhead of
> selection, arbitration, bus settling time, signal deskewing, 
> etc. 

Yeah, that's called "ATAPI".  All IDE CDROMs are SCSI CDROMS
in disguise.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.


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