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From: buck@siswat.UUCP (A. Lester Buck)
Newsgroups: comp.periphs
Subject: Re: Want Start/Stop tape, drives vanishing
Message-ID: <546@siswat.UUCP>
Date: 15 Aug 90 03:53:48 GMT
References: <10780@celit.fps.com>
Organization: Photon Graphics,  Houston
Lines: 23

In article <10780@celit.fps.com>, hutch@fps.com (Jim Hutchison) writes:
> Start/stop tape drives seem to be vanishing from the market place. 

And for good reason, since they are becoming quite uneconomic.  Imagine
the cost for a mechanism that can be moving the tape at 200 ips and
then stop it _and_ start it again, all within the .3in interrecord
gap at 6250 bpi.  These cost tens of thousands of dollars, and they
break down a lot.

Now consider putting your money in an intelligent cache of several
megabytes ($70/MB) and using a much cheaper and simpler streaming mechanism.
Assuming you have enough cache on board, you can simulate start/stop
behaviour _exactly_ while saving a huge amount of money.

Even IBM's top of the line 3480 drive, transferring at a constant 3 MB/sec,
is basically a streaming tape drive, although a very high performance
version.  And all the latest tape developments are coming in helical scan
technology, which is much more a streaming technology than start/stop.
Helical scan is based on a high head to medium relative velocity, which
means the tape has to be "streaming" before any data can be written.

-- 
A. Lester Buck    buck@siswat.lonestar.org  ...!uhnix1!moray!siswat!buck