cass38 tape changer
-------------------

Some information about how to use the changer part of this follows.
The tape bit just behaves the same as a normal drive, except that mt
offline doesn't work -- it seems to get into a screwed up state where
the drive and changer don't agree about where the tape has got to.
The software I'm using is the same as on Linux, so we'll be able to
keep the same interface when it moves to a PC.

The changer part is controlled via mtx, an mt-like changer interface,
installed to /home/jmi/bin/mtx.  Each invocation of this will need a
device specification, ie.

/home/jmi/bin/mtx -f /dev/changer command

Possible commands are:

status
  Reports on the contents of the loader magazine and the tape drive(s).
load <slotnum>
  Loads the tape from <slotnum> (numbered from 1) into the drive.
unload [<slotnum>]
  Unloads the tape in the drive into slot <slotnum>.  Defaults to
  unloading the tape into the slot it was originally loaded from.
first
  Loads the first tape in the magazine into the drive.
last
  Loads the last tape in the magazine into the drive.
next
  Loads the next tape in the sequence.

The first, next, last commands all unload the drive first (same as
unload) before loading the next tape.

I have a wrapper Perl script for ufsdump to implement tape changing
via calls to mt (to rewind the tape) and mtx (to operate the changer)
in ~jmi/perl/autodump (NOTE: this has NOT yet been tested).  For tar,
use gtar in multi-volume mode with a tape change script similar to the
one below:

--cut--
#!/bin/sh
#
# Tape change script for cass38's autoloader.  Intended to be run from
# GNU tar via the -F option.
#

MTX=/home/jmi/bin/mtx

# Rewind it first.
mt -f /dev/rmt/0n rewind || exit 1

# Instruct the changer to load the next tape.
$MTX -f /dev/changer next || exit 1

exit 0
--cut--

Then do gtar -F /path/to/script.  Obviously an rsh will need inserting
if you are using the tape drive remotely (much more likely to be using
dump here though).

--
Jonathan Irwin (jmi@ast.cam.ac.uk)


=======================================================================

To load first tape:

/home/jmi/bin/mtx -f /dev/changer first

To check status:

/home/jmi/bin/mtx -f /dev/changer status

Then to do multi-tape dump, cd to appropriate place:

gtar -F /home/mike/tape-change -cvf /dev/rmt/0cn .