Bacula manual changer script

Bacula is a really nice backup program except for two minor flaws:

The manual tape changing requires user interaction with the bacula console.
It is not possible to alter the size of the internal buffers, which is slowing the backup down a bit (they are too small).

Well I can't change something on the second point but I can on the first.
Bacula supports a variety of tape changers through the use of mtx-changer scripts/programs. This highly flexible approach allowed me to create this shell script which does the following:
Whenever a new tape is required it sends a mail to the operator to insert the new tape. Then it wait's until a tape has been inserted, sends a mail again to say thank you and let's bacula continue it's backup.
So you can schedule and run backups without ever having to log on or see the console. To make the whole thing work you need to create a Device resource which looks something like this ("Archive Device", "Maximum Changer Wait", "Media Type" and "Label media" may have different values):

Device {
   Name=DDS3
   Archive Device = /dev/nsa0				# use yours not mine! ;)
   Changer Device = /dev/nsa0				# not really required
   Changer Command = "/usr/local/bin/mtx-changer %o %a %S"	# use this (maybe change the path)!
   Maximum Changer Wait = 259200			# 3 days in seconds
   AutomaticMount = yes;				# mount on start
   AlwaysOpen = yes;					# keep device locked
   Media Type = DDS3					# it's just a name
   RemovableMedia = yes;				# 
   Offline On Unmount = Yes;				# keep this too
   Label media = Yes;					# 
}

As the script has to emulate the complete wisdom of a mtx-changer it has an internal "database" where which tape is stored, you can see this at that line:

labels="VOL-0001 VOL-0002 VOL-0003 VOL-0004 VOL-0005 VOL-0006 VOL-0007 VOL-0008 VOL-0009 VOL-0010 VOL-0011 VOL-0012"

This effectivly tells that volume "VOL-0001" is located in slot 1 (which is our lowest slot), that volume "VOL-0002" is located in slot 2 and so on..
The script also maintains a logfile (/var/log/mtx.log) where you can monitor its operation.

If you have any questions, problems or suggestions to this script, please let me know.

And finally the script itself if you like to have a look before you download..:

#!/bin/sh
#
# Bacula interface to mtx autoloader
#
#   Created  OCT/31/03 by Alexander Kuehn, derived from Ludwig Jaffe's script
#
#  Works with the HP C1537A L708 DDS3
#
#set -x
# these are the labels of the tapes in each virtual slot, not the slots!
labels="VOL-0001 VOL-0002 VOL-0003 VOL-0004 VOL-0005 VOL-0006 VOL-0007 VOL-0008 VOL-0009 VOL-0010 VOL-0011 VOL-0012"

# who to send a mail to?
recipient=root@localhost
logfile=/var/log/mtx.log

# Delay in seconds how often to check whether a new tape has been inserted
TAPEDELAY=10	# the default is every 10 seconds
echo `date` ":" $@ >>$logfile

# change this if mt is not in the path (use different quotes!)
mt=`which mt`
grep=`which grep`
#
# how to run the console application?
console="/usr/local/sbin/console -c /usr/local/etc/console.conf"

command="$1"

#TAPEDRIVE0 holds the device/name of your 1st and only drive (Bacula supports only 1 drive currently)
#Read TAPEDRIVE from command line parameters
if [ -z "$2" ] ; then
  TAPEDRIVE0=/dev/nsa0 
else
  TAPEDRIVE0=$2 
fi

#Read slot from command line parameters
if [ -z "$3" ] ; then
  slot=`expr 1`
else
  slot=`expr $3`
fi

if [ -z "$command" ] ; then
  echo ""
  echo "The mtx-changer script for Bacula"
  echo "---------------------------------"
  echo ""
  echo "usage: mtx-changer <command> <devicename of tapedrive> [slot]"
  echo "       mtx-changer"
  echo ""
  echo "Valid commands:"
  echo ""
  echo "unload          Unloads a tape into the slot"
  echo "                from where it was loaded."
  echo "load <slot>     Loads a tape from the slot <slot>"
  echo "list            Lists full storage slots"
  echo "loaded          Gives slot from where the tape was loaded."
  echo "                0 means the tape drive is empty."
  echo "slots           Gives Number of avialable slots." 
  echo "volumes         List avialable slots and the label of the." 
  echo "                tape in it (slot:volume)"
  echo "Example:"
  echo "  mtx-changer load /dev/nst0 1   loads a tape from slot1"
  echo "  mtx-changer %a %o %S   "
  echo ""
  exit 0
fi


case "$command" in 
	unload)
		# At first do mt -f /dev/st0 offline to unload the tape 
		#
		# Check if you want to fool me
		echo "unmount"|$console >/dev/null 2>/dev/null
		echo "mtx-changer: Checking if drive is loaded before we unload. Request unload" >>$logfile
		if $mt -f $TAPEDRIVE0 status >/dev/null 2>/dev/null ; then		# mt says status ok
			echo "mtx-changer: Doing mt -f $TAPEDRIVE0 rewoffl to rewind and unload the tape!" >>$logfile
			$mt -f $TAPEDRIVE0 rewoffl
		else
			echo "mtx-changer:  *** Don't fool me! *** The Drive $TAPEDRIVE0 is empty." >>$logfile
		fi
		exit 0
		;;
	
   load)
		#Let's check if drive is loaded before we load it
		echo "mtx-changer: Checking if drive is loaded before we load. I Request loaded" >>$logfile
		LOADEDVOL=`echo "status Storage"|$console|$grep $TAPEDRIVE0|grep ^Device|grep -v "not open."|grep -v "ERR="|grep -v "no Bacula volume is mounted"|sed -e s/^.*Volume\ //|cut -d\" -f2`
#		if [ -z "$LOADEDVOL" ] ; then 	# this is wrong, becaus Bacula would try to use the tape if we mount it!
#			LOADEDVOL=`echo "mount"|$console|$grep $TAPEDRIVE0|grep Device|grep -v "not open."|grep -v "ERR="|sed -e s/^.*Volume\ //|cut -d\" -f2`
#			if [ -z "$LOADEDVOL" ] ; then 
#				echo "mtx-changer: The Drive $TAPEDRIVE0 is empty." >>$logfile
#			else							# restore state?
#				if [ $LOADEDVOL = $3 ] ; then 		# requested Volume mounted -> exit
#					echo "mtx-changer: *** Don't fool me! *** Tape $LOADEDVOL is already in drive $TAPEDRIVE0!" >>$logfile
#					exit
#				else					# oops, wrong volume
#					echo "unmount"|$console >/dev/null 2>/dev/null
#				fi
#			fi
#		fi
		if [ -z "$LOADEDVOL" ] ; then
			echo "unmount"|$console >/dev/null 2>/dev/null
			LOADEDVOL=0
		else
			#Check if you want to fool me
			if [ $LOADEDVOL = $3 ] ; then 
				echo "mtx-changer: *** Don't fool me! *** Tape $LOADEDVOL is already in drive $TAPEDRIVE0!" >>$logfile
				exit
			fi
			echo "mtx-changer: The Drive $TAPEDRIVE0 is loaded with the tape $LOADEDVOL" >>$logfile
			echo "mtx-changer: Unmounting..." >>$logfile
			echo "unmount"|$console >/dev/null 2>/dev/null
		fi
		echo "mtx-changer: Unloading..." >>$logfile
		echo "mtx-changer: Doing mt -f $TAPEDRIVE0 rewoffl to rewind and unload the tape!" >>$logfile
		mt -f $TAPEDRIVE0 rewoffl 2>/dev/null
		#Now we can load the drive as desired 
		echo "mtx-changer: Doing mtx -f $1 $2 $3" >>$logfile
		# extract label for the mail
		count=`expr 1`
		for label in $labels ; do
			if [ $slot -eq $count ] ; then volume=$label ; fi
			count=`expr $count + 1`
		done

		mail -s "Bacula needs volume $volume." $recipient <<END_OF_DATA
Please insert volume $volume from slot $slot into $TAPEDRIVE0 .
Kind regards,
Bacula.
END_OF_DATA
		sleep 15
		$mt status >/dev/null 2>/dev/null
		while [ $? -ne 0 ] ; do
			sleep $TAPEDELAY
			$mt status >/dev/null 2>/dev/null
		done
		mail -s "Bacula says thank you." $recipient <<END_OF_DATA
Thank you for inserting the new tape! (I requested volume $volume from slot $slot.)
Kind regards,
Bacula.
END_OF_DATA
		echo "Successfully loaded a tape into drive $TAPEDRIVE0 (requested $volume from slot $slot)." >>$logfile
		echo "Loading finished." ; >>$logfile
		echo "$slot"
		exit 0
		;;

	list) 
		echo "mtx-changer: Requested list" >>$logfile
		LOADEDVOL=`echo "status Storage"|$console|$grep $TAPEDRIVE0|grep ^Device|grep -v "not open."|grep -v "ERR="|grep -v "no Bacula volume is mounted"|sed -e s/^.*Volume\ //|cut -d\" -f2`
		if [ -z $LOADEDVOL ] ; then		# try mounting
			LOADEDVOL=`echo "mount"|$console|$grep $TAPEDRIVE0|grep Device|grep -v "not open."|grep -v "ERR="|sed -e s/^.*Volume\ //|cut -d\" -f2`
			if [ -z $LOADEDVOL ] ; then		# no luck
				LOADEDVOL="_no_tape"
			else							# restore state
				echo "unmount"|$console >/dev/null 2>/dev/null
			fi
		fi
		count=`expr 1`
		for label in $labels ; do
			if [ "$label" != "$LOADEDVOL" ] ; then
				printf "$count "
			fi
			count=`expr $count + 1`
		done
		printf "\n"
      ;;

   loaded)
		echo "mtx-changer: Request loaded, dev $TAPEDRIVE0" >>$logfile
		LOADEDVOL=`echo "status Storage"|$console|$grep $TAPEDRIVE0|grep ^Device|grep -v "not open."|grep -v "ERR="|grep -v "no Bacula volume is mounted"|sed -e s/^.*Volume\ //|cut -d\" -f2`
		if [ -z $LOADEDVOL ] ; then
			LOADEDVOL=`echo "mount"|$console|$grep $TAPEDRIVE0|grep Device|grep -v "not open."|grep -v "ERR="|grep -v "no Bacula volume is mounted"|sed -e s/^.*Volume\ //|cut -d\" -f2`
			if [ -z "$LOADEDVOL" ] ; then		# no luck
				echo "$TAPEDRIVE0 not mounted!" >>$logfile
			else							# restore state
				echo "unmount"|$console >/dev/null 2>/dev/null
			fi
		fi
		if [ -z "$LOADEDVOL" ] ; then 
			LOADEDVOL="_no_tape" >>$logfile
			echo "0"
		else
			count=`expr 1`
			for label in $labels ; do
				if [ $LOADEDVOL = $label ] ; then echo $count ; fi
				count=`expr $count + 1`
			done
		fi
		exit 0
		;;

   slots)
		echo "mtx-changer: Request slots" >>$logfile
		count=`expr 0`
		for label in $labels ; do
			count=`expr $count + 1`
		done
		echo $count
      ;;

   volumes)
		echo "mtx-changer: Request volumes" >>$logfile
		count=`expr 1`
		for label in $labels ; do
			printf "$count:$label "
			count=`expr $count + 1`
		done
		printf "\n"
      ;;
esac