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TapeChanger::MTX - use 'mtx' to manipulate a tape library
use TapeChanger::MTX; my $loaded = TapeChanger::MTX->loadedtape; print "Currently loaded: $loaded\n" if ($loaded); TapeChanger::MTX->loadtape('next'); my $nowloaded = TapeChanger::MTX->loadedtape; print "Currently loaded: $nowloaded\n" if ($nowloaded);
See below for more available functions.
TapeChanger::MTX is a module to manipulate a tape library using the 'mtx' tape library program. It is meant to work with a simple shell/perl script to load and unload tapes as appropriate, and to provide a interface for more complicated programs to do the same. The below functions and variables should do as good a job as explaining this as anything.
- $TapeChanger::MTX::MT =item $TapeChanger::MTX::MTX
What is the location of the 'mt' and 'mtx' binaries? Can be set with '$MT' and '$MTX' in ~/.mtxrc, or defaults to '/usr/sbin/mt' and '/usr/local/sbin/mtx'.
What are the names of the tape (DRIVE) and changer (CONTROL) device nodes? Can be set with $DRIVE or $CONTROL in ~/.mtxrc, or default to '/dev/rmt/0' and '/dev/changer' respectively.
Does the tape drive have to eject the tape before the changer retrieves it? It's okay to say 'yes' if it's not necessary, in most cases. Can be set with $EJECT in ~/.mtxrc, or defaults to '1'.
How long should we wait to see if the drive is ready, in seconds, after mounting a volume? Can be set with $READY_TIME in ~/.mtxrc, or defaults to 60.
Print debugging information? Set to '0' for normal verbosity, '1' for debugging information, or '-1' for 'quiet mode' (be as quiet as possible).
This module uses the following functions:
- tape_cmd ( COMMAND )
- mt_cmd ( COMMAND )
Runs 'mtx' and 'mt' as appropriate.
COMMANDis the command you're trying to send to them. Uses 'warn()' to print the commands to the screen if $TapeChanger::MTX::DEBUG is set.
- numdrives ()
- numslots ()
- loadedtape ()
- numloaded ()
- nummailslots ()
Returns the number of drives, number of slots, currently loaded tape, number of loaded tapes, and number of Import/Export slots, respectively, by parsing tape_cmd('status'). Not all of these will apply to all tape drives.
- slothash ()
Returns a hash table (not hashref) of information about each slot. The keys of the hash are the slot numbers, and the values are arrayrefs that contain three fields:
SlotType "Import/Export" or empty string Full "Full" or "Empty" VolumeTag Tape barcode, if it exists
- drivehash ()
As with slothash, but looks at the drives instead of the slots.
- loadtape ( SLOT [, DRIVE] )
Loads a tape into the tape changer, and waits until the drive is again ready to be written to.
SLOTcan be any of the following (with the relevant function indicated):
current C<loadedtape()> prev C<loadprevtape()> next C<loadnexttape()> first C<loadfirsttape()> last C<loadlasttape()> 0 C<_ejectdrive()> 1..99 Loads the specified tape number, ejecting whatever is currently in the drive.
DRIVEis the drive to load, and defaults to 0. Returns 0 if successful, an error string otherwise.
- loadnexttape ()
- loadprevtape ()
- loadfirsttape ()
- loadlasttape ()
Loads the next, previous, first, and last tapes in the changer respectively. Use tape_cmd('next'), tape_cmd('previous'), tape_cmd('first'), and tape_cmd('last'), respectively.
- transfertape ( FROM, TO )
Transfers a tape from slot
TO. Returns 0 on success. Makes sure the necessary slots are empty/full as appropriate.
- tagtoslot ( TAG )
Returns the slot that the tape with volume tag
TAGis in, or '0' if it's not in the tape changer.
- slottotag ( SLOT )
Returns the volume tag of the tape in slot
SLOT, or '' if there is no tag or tape.
- tagtodrive ( TAG )
Returns the drive that the tape with volume tag
TAGis in, or '-1' if it's not in a drive.
- drivetotag ( DRIVE )
Returns the volume tag of the tape in drive
DRIVE, or '' if there is no tag or tape.
- ejecttape ()
Ejects the tape, by first ejecting the tape from the drive (mt_cmd(rewind) then mt_cmd(offline)) and then returning it to its slot (tape_cmd(unload)). Returns 1 if successful, 0 otherwise.
- resetchanger ()
Resets the changer, ejecting the tape and loading the first one from the changer.
- checkdrive ()
Checks to see if the drive is ready or not, by waiting for up to $TapeChanger::MTX::READY_TIME seconds to see if it can get status information using mt_cmd(status). Returns 1 if so, 0 otherwise.
Returns a string containing the loaded tape and the drive that it's mounted on.
- inventory ()
Runs a tape inventroy, if supported by the tape changer. This works out volume tags and such.
- cannot_run ()
Does some quick checks to see if you're actually capable of using this module, based on your user permissions. Returns a list of problems if there are any, 0 otherwise.
~/.mtxrc is automatically loaded when this module is used, if it exists, using do(). This could cause security problems if you're trying to use this with setuid() programs - so just don't do that. If you want someone to have permission to mess with the tape drive and/or changer, let them have that permission directly.
Perl 5.6.0 or better, an installed 'mtx' binary, and a tape changer and reader connected to the system.
Theoretically allows multiple drives per changer and I/E slots, but I haven't tested it, so I may have missed something. 'load previous' doesn't actually work, because mtx doesn't support it (though the help says it does).
mtx, mt, tapechanger. Inspired by stc-changer, which comes with the AMANDA tape backup package (http://www.amanda.org), and MTX, available at http://mtx.sourceforge.net.
Tim Skirvin <firstname.lastname@example.org>.
Code for multi-slot tape drives and volume tags from Hubert Mikulicz <email@example.com>.
This code is distributed under the University of Illinois Open Source License. See
http://www.ks.uiuc.edu/Development/MDTools/tapechanger-mtx/license.html for details.
Copyright 2001-2004 by the University of Illinois Board of Trustees and Tim Skirvin <firstname.lastname@example.org>.