Ubuntu Manpage: mtx - control SCSI media changer devices

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
                 omitted, 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
                 capable 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
                 <operation> 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
                 documentation).

       [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).

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

       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.

       eject     Eject the tape currently in the drive.

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
command 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
particular, 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
operating 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
       /kernel/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
       <robertnelson@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://sourceforge.net/projects/mtx.