After much digging around I found a way to always have my tape configured for
no hardware compression without my constantly having to turn it off.

Here's what I did.

I create a /etc/stinit.def file with the following entries:

# Quantum SDLT220
manufacturer=QUANTUM model="SuperDLT1" {
timeout=3600
long-timeout=14400
mode1 blocksize=0 density=0x48 compression=1 # SDLT220 density, compression
on
mode2 blocksize=0 density=0x48 compression=0 # SDLT220 density, compression
off
mode3 blocksize=0 density=0x41 compression=1 # SDLT8000 density, compression
on
mode4 blocksize=0 density=0x41 compression=0 # SDLT8000 density, compression
off
}

A amtapetype returned the following:

define tapetype sdlt220nocomp {
    comment "just produced by tapetype prog (hardware compression off)"
    length 109539 mbytes
    filemark 0 kbytes
    speed 10351 kps
}


This came out of a document I found on the Quantum Website.


Then I created a script in /etc/init.d linked into /etc/rc5.d called amanda:

#!/bin/bash
#
# amanda        This shell script processes needed commands
#               to support an amanda server
#
# Author:       Chris Davis
#
# description:  Configure correct tape devices on system
# processname:  yum

# source function library
. /etc/rc.d/init.d/functions


RETVAL=0

start() {
        echo -n $"Configuring tape devices for amanda: "
        /sbin/stinit && chmod g+w /dev/*st0*
        RETVAL=$?
        echo
}

stop() {
        echo -n $"Nothing to deconfigure for amanda: "
        RETVAL=$?
        echo
}

restart() {
        stop
        start
}

case "$1" in
  start)
        start
        ;;
  stop) 
        stop
        ;;
  *)
        echo $"Usage: $0 {start|stop}"
        exit 1
esac

exit $RETVAL



So everytime the box reboots this script calles stinit which reads the
stinit.def file and makes sure the disk group has write access to the tapes.

I can then use the devices /dev/nst0l and /dev/st0l (the mode 2 device) and
hardware compression is always turned off.  When I use a tape for the first
time I make sure to clean off its header using the script that somebody
supplied earlier when I was asking about turning hardware compression off.


This has been working great in my testing - now I just have to find out how to
set it up correctly for a LTO 1 drive on a different machine.




Chris