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From: bruce@opus.objy.com (Bruce Reed)
Newsgroups: comp.unix.ultrix
Subject: Re: DAT tape lengths
Message-ID: <1991May17.061139.5673@objy.com>
Date: 17 May 91 06:11:39 GMT
References: <1991May15.073454.11808@hollie.rdg.dec.com> <1991May15.012025.2766@ux1.cso.uiuc.edu> <1991May15.154453.26014@mlb.semi.harris.com> <1991May15.193256.7697@raven.alaska.edu>
Sender: news@objy.com
Reply-To: bruce@opus.objy.com (Bruce Reed)
Organization: Objectivity Inc.
Lines: 27

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.

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.

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.

Incidentally, 8mm tapes are packaged and marketed in a similar way. A
120 minute "video quality" 8mm tape is equivalent to a 112 meter data
tape. This format is not particularly known for it's long life (write
retries on the first pass!) and I've found that the data variety
wears just as bad as the audio tapes.

-- 
Bruce Reed        				
Objectivity Inc.              bruce@objy.com 	| Duck em' if they can't
Menlo Park, CA                sun!objy!bruce	| take a joke!