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From: ddr@flux.isr.alaska.edu (Donald D Rice)
Newsgroups: comp.unix.ultrix
Subject: Re: DAT tape lengths
Message-ID: <1991May17.180849.13840@raven.alaska.edu>
Date: 17 May 91 18:08:49 GMT
References: <1991May15.154453.26014@mlb.semi.harris.com> <1991May15.193256.7697@raven.alaska.edu> <1991May17.061139.5673@objy.com>
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In article <1991May17.061139.5673@objy.com> bruce@opus.objy.com (Bruce Reed) writes:
>I've used both standard audio and data DATs, though never DEC's. The
>audio tapes are marked in minutes and come in 60, 90, and 120 minute
>varieties. I've only seen the data version sold in 60 meter lengths.
>A 120 minute audio DAT is equivalent to the 60 meter data DAT.
>
That would make sense.  I got to thinking about it and it takes us about 90
minutes to dump about 800 MB, so 1.2 GB would take about 120 minutes...
therefore 60m = 120 min = 1.2 GB.

>I ran a few capacity tests to verify the above and found that I could
>not reliably read a 90 minute audio DAT written on an HP DDS drive. I
>would think the length would only affect the capacity, so perhaps I
>had a bad tape to begin with.
>
Not necessarily.  One vendor told me that their DAT drives would not
work reliably with 45m tapes...didn't say why, but recommended using only
60m tapes.  That's why I've stuck with DEC's tapes, which are clearly marked
as 60m.  Besides, their price is competitive.

>I can't make any performance claims for data versus audio DATs. I have
>written my 120 minute audio DATs several times and have no problems
>recovering data. I'm sure the data DATs have higher quality tape and
>superior shells, but I think the data versus audio distinction is more
>of a marketing ploy which allows tape manufacturers to charge twice as
>much.
>
I want one of those dual-purpose drives that plays audio DATs as well as
doing data DATs so we can get use out of the drive between backups.  I
wonder if any of the "jukebox" data DATs can play audio tapes?  Maybe even
include disk jockey software..."the latest in AC (Artificial Cool) technology
brings the Top Ten to your DECstation."  I hope DEC's engineers are hard at
work on the concept.
You can tell, it is Friday and I'm ready for the weekend.
>
>-- 
>Bruce Reed        				
>Objectivity Inc.              bruce@objy.com 	| Duck em' if they can't
>Menlo Park, CA                sun!objy!bruce	| take a joke!


-- 
Don Rice                                  Internet: ddr@flux.isr.alaska.edu
Geophysical Institute                     E-mail:   fnddr@alaska.bitnet
University of Alaska                      Phone:    (907) 474-7569
Fairbanks, AK 99775                       Loran:    64.86N 212.16E