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From: chris@com50.c2s.mn.org (Chris Johnson)
Newsgroups: comp.periphs.scsi
Subject: Re: Helical scan tape vs QIC
Keywords: QIC DAT 8mm
Message-ID: <1990Dec4.194504.28493@com50.c2s.mn.org>
Date: 4 Dec 90 19:45:04 GMT
References: <363@adphdw20.UUCP>
Organization: Com Squared Systems, Inc.
Lines: 51

In article <363@adphdw20.UUCP> dtb@adpplz.UUCP (Tom Beach) writes:
>There has been a fair amount of discussion here recently over the relative
>merits of the competing helical scan technologies.
>
>What's the opinion of the readership on the future of QIC technology.
>Using embedded servo track following technology would allow reasonable
>track densities and these cartridges have far and away higher surface
>areas than the small helical scan cartridges.
>
>There will be 1.3 GB QIC drives available for evaluation within the
>next 3 months. That matches today's DAT drives with, in my opinion,
>greater future capacity enhancements than DAT.
>
>I'm not sure that QIC isn't being written off too quickly in this forum.

While it is true that a QIC tape offers far more magnetic tape surface area
than either DAT or 8mm, I wonder if the helical scan technologies are not
able to make more full use of what area is available.  That is, can a
linear parallel track recording method use as much as a helical scan
recording method given the same area passing under the record heads?  I
don't think so, but I'm no expert.  I'd like to see some comments from
some people who might know.

Another advantage helical scan technologies have over QIC at the moment,
is that 4mm and 8mm tape cartridges are much cheaper.  In quantities, QIC
tapes are still close to $20 a pop, while we can get 8mm tapes for $3.xx
each.

The helical scan tapes are also much smaller, physically, allowing smaller
form factors in tape drives, and less space required for archived tape
storage.

Yet another advantage of 4mm and 8mm technologies over QIC is that they are
start/stop tape positioning devices versus streaming tape devices.  If you've
ever watched a QIC tape drive shuffle back and forth, you know what I mean.
QIC devices waste a lot of time repositioning the tape.  Transfer rates
suffer.

On the other hand, if someone could provide a 6+ gigabyte QIC tape cartridge
with 250 kilobyte per second average data transfer time, and sell the tapes
themselves for around $10-12 each, we will buy lots of them.

Right now, optical tape looks like an attractive, soon to be available
archival media, too, for those who do not need to rewrite their media.
If the optical tape media costs can be made low enough, you could essentially
never worry about it.


-- 
   ...Chris Johnson          chris@c2s.mn.org   ..uunet!bungia!com50!chris
 Com Squared Systems, Inc.   St. Paul, MN USA   +1 612 452 9522


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