Path: utzoo!utgpu!watserv1!watmath!att!dptg!lzsc!hcj
From: hcj@lzsc.ATT.COM (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: Re: Tape Drive Backup
Summary: I have a BMS-200, and a 60 Meg Cartridge Tape
Message-ID: <1285@lzsc.ATT.COM>
Date: 12 Feb 90 14:32:04 GMT
References: <17425@laurel.athertn.Atherton.COM> <1990Feb12.015226.25152@gumby.cc.wmich.edu>
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 51

> writes about a tape unit available from BMS:  While I appreciate his sharing
> the info with the net, I honestly can't understand why anyone would choose
> the option he describes over the ICD FA*ST Tape Backup unit.  I don't have

First you need an Atari Host Adapter that handles multiple SCSI correctly.
BMS-200 does this.  ICD FA*ST claims to.  LATE issue SUPRA claim to.

Second ingredient is the Adaptec 3530A Adapter.

Third ingredient is a Archeive or equivalent QIC-36 tape unit.

All in all, its not cheap.  But the best way to back up large HD's.

A note on speed.  The tape units run at the same speed.  For 1:1 formatted
HD's, the software can read in 1 track (17 sectors) while writing it to
tape (using the internal buffer in the 3530A. (for purests, the tape will
only accept 16 sectors at a time, so the HD has to be able to read across
the head switch very quickly.)

The goal is to keep the tape moving continuously.  If at any time it runs 
out of data to write, it must write a long trailer, stop, backspace,and 
wait to restart.  This is really slow.
If the drive doesn't seek fast enough (sh204), the tape stops from
time to time and has to restart.
If formatted 2:1 or worse, the HD allows you to format for 18 sectors/track.
And the backup writes 16 sectors and stops (see above), then restarts.
The Tape sounds busy, but quickly drops to 1 meg a minute or worse.

I have a BMS-200, controlling 1 3530A tape, and 2 Adaptec 4000A connected
to HD's. Formatted 1:1 with my own backup software (derived from BMS's
early work) I get 6-7 megabyte per minute. I definitely appreciate being
ATT and SUN compatible.  (I got Jwahar Bammi to send me all of gnu-xxx
on 1 tape written on a SUN; read it in and go. WOW!). 

I would definitely recommend Cartridge Tape for backup.  The bigger the 
HD, the more you need it.
BMS makes good stuff, it is aimed to the do-it-yourselfer.  ICD has a 
a good sounding product and package.  Either way it is a good way to go.

I save partitions, rather than raw disk by sector number.  This lets be
do two things. One, I can restore a single partition or copy it to another
disk.  Second, by judiciously rewriting tos.c from MINIX, I can actually 
access and read files from the tape directly.  The ultimate for the 
Cartridge Tape is to adapt a CPIO clone (such a gnuxxx) to read and write
the CT.  This is then compatible with UNIX(r), MINIX, and TOS.

Howard C. Johnson
ATT Bell Labs
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