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From: tims@infidel.lanl.gov (Tim Sullivan)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: SCSI confusions, help please!
Message-ID: <TIMS.91May16115641@infidel.infidel.lanl.gov>
Date: 16 May 91 17:56:41 GMT
Sender: news@lanl.gov
Organization: Center for Nonlinear Studies, Los Alamos
Lines: 32


I am confused about the SCSI interface. Let me describe the problem I
was trying to solve and hope that someone can explain why I was wrong.

A Sun network here at the Lab needed more disk space and tape backup,
so they went out and bought an external box from R-Squared that has a
1.2Gbyte hard drive and a 2.3 Gbyte Exabyte tape drive. It interfaces
to a Sun throught the Sun SCSI port. No problem.

Now we have an AT and a frame grabber that takes data off of a video
camera. For something that we want to do, we are limited by the size
of our hard disk, which coincidentally died. So we said, why don't we
replace the dead MFM hard disk with a small SCSI disk and when we need
to we can bring the R-Squared system over and use with the AT? A 150Mb
SCSI drive might cost us $750 or so, and a SCSI controller can be
found for less than $100. So, for less than double the price of an MFM
hard drive of comparable size, we can switch to SCSI and have the
occasional use of the big disk and tape drive.

I've heard that you should buy the SCSI controller from the same
people you buy the disk from, so I looked in the R-Squared catalog and
sure enough, they sell a SCSI controller to attach their drive to an
AT for $1600! And a 91 Mbyte, internal hard drive for $1725! 

So what is wrong here? What is it about SCSI controllers that can
support price differences so large? What does a $1600 controller do
that a $100 controller doesn't do? There must be something I don't
understand. 

Thanks for any help you can offer.

Tim Sullivan (tims@goshawk.lanl.gov)