Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!mips!sgi!jeremy@perf2.asd.sgi.com
From: jeremy@perf2.asd.sgi.com (Jeremy Higdon)
Newsgroups: comp.sys.sgi
Subject: Re: HELP: SGI 4D/360 EXABYTE problem: Command DD
Summary: Use the variable devices for non 1024 byte multiple transfers on Exabyte
Message-ID: <106508@sgi.sgi.com>
Date: 28 May 91 21:44:38 GMT
References: <1991May27.192352.24630@garfield.cs.mun.ca>
Sender: guest@sgi.sgi.com
Distribution: na
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 49

In article <1991May27.192352.24630@garfield.cs.mun.ca>, harold@odie.cs.mun.ca (Harold Wareham(Todd)) writes:
> We are having problems with an EXABYTE-8200 hooked up to an SGI-4D/360
> running SGI UNIX version 3.3.1. Specifically, we cannot read or write 
> an EXABYTE tape using the command DD; however, we can create and read 
> tapes using the command TAR. The drive was cleaned prior to the
> problems described in this message (the same day as the tests
> run below, in fact). To add strangeness to it all, one can use
> DD with a QIC drive, but it refuses to read back the last (partial)
> block from tape.
> 
> Odd, yes? Details follow. If you have any ideas about what's going on,
> drop me a line.
> 
> - Todd
> 
> Todd Wareham	harold@odie.cs.mun.ca	|"Success in science depends not
> Department of Physics        		| only on rational argument but
> Memorial University of Newfoundland	| on a mixture of subterfuge,
> St. John, NF, Canada			| rhetoric, and propaganda"
> 					|    - Feyerabed
> 
> **************************** DETAILS *********************************
> 
> Scripts of the various errors encountered are given below.
> 
> The following is the script of trying to read from our EXABYTE
> drive (/dev/mt/tps0d6) a tape containing a single large file
> (20484 6000-byte records); just to be sure switching from byte-swapping
> to no byte-swapping reads was causing no problems, I popped the
> tape out between the read attempts.
> 
> This tape was created at another EXABYTE drive on campus attached to a 
> MIPS-120 running UNIX 4.3 BSD. This tape reads and writes fine (using 
> DD) on that other system on that other drive.
> 
> 
> Script started on Mon May 27 15:08:34 1991
> % ls -l /dev/mt/tps0d6*
> crw-rw-rw-   3 root     sys       23,192 May 27 14:15 /dev/mt/tps0d6
> crw-rw-rw-   3 root     sys       23,193 May 27 13:57 /dev/mt/tps0d6nr
> crw-rw-rw-   3 root     sys       23,195 Nov  7  1990 /dev/mt/tps0d6nrns
> crw-rw-rw-   3 root     sys       23,194 May 27 14:15 /dev/mt/tps0d6ns

There are no variable mode devices in the /dev/mt directory, so the first
thing you have to do is create them.  cd to /dev and execute the following:

	./MAKEDEV tps

Then use /dev/mt/tps0d6nsv or /dev/mt/tps0d6nrnsv to talk to the Exabyte.