*BSD News Article 82316


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From: dgy@rtd.com (Don Yuniskis)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: whats a good external SCSI tape?
Date: 4 Nov 1996 21:59:12 GMT
Organization: CICDO
Lines: 38
Message-ID: <55lovg$hs0@baygull.rtd.com>
References: <DzHp5B.6Bt.G.nanguo@nanguo.chalmers.com.au> <54dhae$3gs@uriah.heep.sax.de> <54j67v$soq@newsbr.eunet.fr> <BZOzHFO.smartsignal@delphi.com>
NNTP-Posting-Host: seagull.rtd.com

In article <BZOzHFO.smartsignal@delphi.com>,
Jim Nelson  <smartsignal@delphi.com> wrote:
>Frederic MARAND <Frederic.Marand@osinet.fr> writes:
> 
>>It seems many  people dislike helical scan backup units, but I never
>>could figure out why: we've sold tons of them, even to customers

I would attribute it more to folks' comments regarding failures they've
experienced.  "Repeat customers" could just be accepting a certain failure
rate as "normal" -- or, perhaps not experiencing any problems.  They
could also be unaware of other options that exist.  And, lastly, they
could simply be tied to a particular technology for compatibility
with existing software, other tape units within the facility,
preexisting media, etc.

>- Doubtless a fear of the misunderstood.  Helical scan has been used
>successfully for forty years to handle video and data recording.

Yes, but there are differences between "consumer", and "industrial"
grade transports!  The quality and price differential is often a
factor of 3 to 5 times the best "consumer" unit for a moderately
priced industrial unit.  How abundant are consumer DAT drives
(e.g., for *audio*) at 1/5th the price of a DAT tape transport
(assuming the argument that they are "industrial" grade...)

Helical scan has a LOT of moving parts when contrasted, for
example, to DLT.

> Maybe it just sounds
>scary!  Wonder how nervous the anecdote driven would get if they really
>knew how DRAM worked?  Imagine all those precious bit patterns nestled
>in a matrix of myriads of tiny capacitors - Egads!  You mean my data has
>a time constant!  If some thing called refresh doesn't happen my bits do
>what???  Pass transistors?     Huh?  Oh well, back to work.

"LOOK OUT!!!!  HERE COMES AN ALPHA PARTICLE!!!!!"

--don