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From: dwells@fits.acc.Virginia.EDU (Don Wells)
Newsgroups: comp.misc
Subject: Re: Doubling Tape Capacity: Beware!
Message-ID: <1990Jul20.193412.18146@murdoch.acc.Virginia.EDU>
Date: 20 Jul 90 19:34:12 GMT
References: <413@demott.COM>
Sender: dwells@fits.cx.nrao.edu
Reply-To: dwells@fits.cx.nrao.edu
Organization: National Radio Astronomy Observatory, Charlottesville, VA
Lines: 32

In article <413@demott.COM> kdq@demott.COM (Kevin D. Quitt) writes:
>
>    Be careful about the "doubled" tape capacity.  One Exabyte OEM
>mentioned this to me and explained that it was achieved by compressing
>the data before it was being stored.  

I suspect that there is some confusion going on here. True,
compression options are going to appear for essentially *all* of the
cartridge devices.  BUT! Several of the media are not operating at
their theoretical limits in packing density. The Digidata 12.5mm
cartridges and the Exabyte 8mm cartridges are in this category, and
both are capable of density doubling.  My understanding was that the
Exabyte 5_GB option is a real doubling.

>Since what we put on tape is
>already compressed, we won't see any such gain.

If you are right that the Exabyte 5_GB option is simply compression,
then there will be no gain on data that is already compressed. 

>Kevin D. Quitt         demott!kdq   kdq@demott.com
>DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
>VOICE (818) 988-4975   FAX (818) 997-1190  MODEM (818) 997-4496 PEP last

There is another rumor about the Exabyte 5 GB option that I have heard:
5_GB drives cannot read/write 2.3_GB tapes!

Donald C. Wells, Associate Scientist | NSFnet: dwells@nrao.edu [192.33.115.2]
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