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MTX(1)											   MTX(1)

NAME
       mtx - control SCSI media changer devices

SYNOPSIS
       mtx [-f <scsi-generic-device>] [nobarcode] [invert] [noattach] command [ command ... ]

DESCRIPTION
       The  mtx command controls single or multi-drive SCSI media changers such as tape changers,
       autoloaders, tape libraries, or optical media jukeboxes.  It can also be used  with  media
       changers that use the 'ATTACHED' API, presuming that they properly report the MChanger bit
       as required by the SCSI T-10 SMC specification.

OPTIONS
       The first argument, given following -f , is the SCSI generic device corresponding to  your
       media  changer.	 Consult  your operating system's documentation for more information (for
       example, under Linux these are generally /dev/sg0 through /dev/sg15, under  FreeBSD  these
       are /dev/pass0 through /dev/passX, under SunOS it may be a file under /dev/rdsk).

       The  'invert'  option will invert (flip) the media (for optical jukeboxes that allow such)
       before inserting it into the drive or returning it to the storage slot.

       The 'noattach' option forces the regular media changer  API  even  if  the  media  changer
       incorrectly reported that it uses the 'ATTACHED' API.

       The  'nobarcode'  option  forces  the loader to not request barcodes even if the loader is
       capable of reporting them.

       Following these options there may follow one or more robotics control commands. Note  that
       the 'invert' and 'noattach' options apply to ALL of robotics control commands.

COMMANDS
       --version Report the mtx version number (e.g. mtx 1.2.8) and exit.

       inquiry	 Report  the  product type (Medium Changer, Tape Drive, etc.), Vendor ID, Product
		 ID, Revision, and whether this uses the Attached Changer API (some  tape  drives
		 use  this  rather  than  reporting  a	Medium	Changer on a separate LUN or SCSI
		 address).

       noattach  Make further commands	use  the  regular  media  changer  API	rather	than  the
		 _ATTACHED  API,  no  matter  what  the  "Attached" bit said in the Inquiry info.
		 Needed with some brain-dead changers that report Attached bit but don't  respond
		 to _ATTACHED API.

       inventory Makes	the robot arm go and check what elements are in the slots. This is needed
		 for a few libraries like the Breece Hill ones that do	not  automatically  check
		 the tape inventory at system startup.

       status	 Reports  how  many  drives and storage elements are contained in the device. For
		 each drive, reports whether it has media loaded in it, and  if  so,  from  which
		 storage  slot the media originated. For each storage slot, reports whether it is
		 empty or full, and if the media changer has a bar  code,  MIC	reader,  or  some
		 other	way  of  uniquely identifying media without loading it into a drive, this
		 reports the volume tag and/or alternate volume tag for each piece of media.  For
		 historical  reasons  drives  are  numbered from 0 and storage slots are numbered
		 from 1.

       load <slotnum> [ <drivenum> ]
		 Load media from slot <slotnum> into drive <drivenum>. Drive 0 is assumed if  the
		 drive number is omitted.

       unload [<slotnum>] [ <drivenum> ]
		 Unloads  media from drive <drivenum> into slot <slotnum>. If <drivenum> is omit-
		 ted, defaults to drive 0  (as	do  all  commands).   If  <slotnum>  is  omitted,
		 defaults to the slot that the drive was loaded from. Note that there's currently
		 no way to say 'unload drive 1's media to the slot it came from', other  than  to
		 explicitly use that slot number as the destination.

       [eepos <operation>] transfer <slotnum> <slotnum>
		 Transfers  media from one slot to another, assuming that your mechanism is capa-
		 ble of doing so. Usually used to  move  media	to/from  an  import/export  port.
		 'eepos' is used to extend/retract the import/export tray on certain mid-range to
		 high end tape libraries (if, e.g., the tray was  slot	32,  you  might  say  say
		 'eepos  1  transfer  32 32' to extend the tray).  Valid values for eepos <opera-
		 tion> are 0 (do nothing to the import/export tray), 1, and 2 (what 1  and  2  do
		 varies  depending upon the library, consult your library's SCSI-level documenta-
		 tion).

       [eepos <operation>] [invert] [invert2] exchange <slotnum> <slotnum> [<slotnum>]
		 Move medium from the first slot to the second slot, placing the medium currently
		 in  the  second  slot either back into the first slot or into the optional third
		 slot.

       first [<drivenum>]
		 Loads drive <drivenum> from the first slot in the  media  changer.  Unloads  the
		 drive	if  there  is  already	media in it (note: you may need to eject the tape
		 using your OS's tape control commands first).	Note that this command may not be
		 what  you want on large tape libraries -- e.g. on Exabyte 220, the first slot is
		 usually a cleaning tape. If <drivenum> is omitted, defaults to first drive.

       last [<drivenum>]
		 Loads drive <drivenum> from the last slot in  the  media  changer.  Unloads  the
		 drive	if  there  is already a tape in it. (Note: you may need to eject the tape
		 using your OS's tape control commands first).

       next [<drivenum>]
		 Unloads the drive and loads the next tape in sequence. If the drive  was  empty,
		 loads the first tape into the drive.

       position <slotnum>
		 Positions  the  robot at a specific slot. Needed by some changers to move to and
		 open the import/export, or mailbox, slot.

AUTHORS
       The original 'mtx' program was written by Leonard  Zubkoff  and	extensively  revised  for
       large multi-drive libraries with bar code readers by Eric Lee Green <eric@badtux.org>. See
       'mtx.c' for other contributors.

BUGS AND LIMITATIONS
       You may need to do a 'mt offline' on the tape drive to eject the tape before you can issue
       the  'mtx  unload' command. The Exabyte EZ-17 and 220 in particular will happily sit there
       snapping the robot arm's claws around thin air trying to grab a tape that's not there.

       For some Linux distributions, you may need to re-compile the kernel to scan SCSI LUN's  in
       order to detect the media changer. Check /proc/scsi/scsi to see what's going on.

       If  you	try to unload a tape to its 'source' slot, and said slot is full, it will instead
       put the tape into the first empty slot. Unfortunately the  list	of  empty  slots  is  not
       updated	between  commands on the command line, so if you try to unload another drive to a
       full 'source' slot during the same invocation of 'mtx', it will try to unload to the  same
       (no longer empty) slot and will urp with a SCSI error.

       This program reads the Mode Sense Element Address Assignment Page (SCSI) and requests data
       on all available elements. For larger libraries (more than a couple dozen  elements)  this
       sets  a	big Allocation_Size in the SCSI command block for the REQUEST_ELEMENT_STATUS com-
       mand in order to be able to read the entire result of a big tape library.  Some	operating
       systems	may not be able to handle this. Versions of Linux earlier than 2.2.6, in particu-
       lar, may fail this request due to inability to find contiguous pages  of  memory  for  the
       SCSI  transfer  (later versions of Linux 'sg' device do scatter-gather so that this should
       no longer be a problem).

       The eepos command remains in effect for all further commands on a command line.	Thus  you
       might want to follow eepos 1 transfer 32 32 with eepos 0 as the next command (which clears
       the eepos bits).

       Need a better name for 'eepos' command! ('eepos' is the name  of  the  bit  field  in  the
       actual low-level SCSI command, and has nothing to do with what it does).

       This  program has only been tested on Linux with a limited number of tape loaders (a dual-
       drive Exabyte 220 tape library, with bar-code reader and 21 slots, an Exabyte EZ-17 7-slot
       autoloader,  and a Seagate DDS-4 autochanger with 6 slots). It may not work on other oper-
       ating systems with larger libraries, due to the big SCSI request  size.	 Please  see  the
       projecdt  page  http://sourceforge.net/projects/mtx  for  information  on  reporting bugs,
       requesting features and the mailing list for peer support.

HINTS
       Under Linux, cat /proc/scsi/scsi will tell you what SCSI devices you have.  You	can  then
       refer to them as /dev/sga, /dev/sgb, etc. by the order they are reported.

       Under  FreeBSD,	camcontrol  devlist  will tell you what SCSI devices you have, along with
       which pass device controls them.

       Under Solaris, set up your 'sgen' driver so that it'll look for tape changers  (see  /ker-
       nel/drv/sgen.conf  and  the  sgen  man page), type touch /reconfigure then reboot. You can
       find your changer in /devices by typing /usr/sbin/devfsadm  -C  to  clean  out  no-longer-
       extant  entries	in  your /devices directory, then find /devices -name \*changer -print to
       find the device name. Set the symbolic link /dev/changer to point to that device name  (if
       it is not doing so already).

       With  BRU,  set	your  mount  and  unmount  commands  as  described on the BRU web site at
       http://www.bru.com to move to the next tape when backing up or restoring.  With	GNU  tar,
       see mtx.doc for an example of how to use tar and mtx to make multi-tape backups.

AVAILABILITY
       This   version  of  mtx	is  currently  being  maintained  by  Robert  Nelson  <robertnel-
       son@users.sourceforge.net> .  The 'mtx' home page is  http://mtx.sourceforge.net  and  the
       actual	code   is   currently	available   there   and   via	SVN  from  http://source-
       forge.net/projects/mtx.

SEE ALSO
       mt(1),loaderinfo(1),tapeinfo(1),scsitape(1),scsieject(1)

					      MTX1.3					   MTX(1)
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