Frequently Asked Questions List, v 1.0.1

Index: 
  I. Compiling
  II. Finding the correct device
  III. Operational Issues

Part I: Compiling.

Q: Where is the Makefile in the tarball?
A: MTX now uses GNU Autoconf to generate the Makefile. Type "./configure"
   while in the extracted mtx directory. 

Q: Typing 'make' gives me a bunch of errors in the Makefile. Why can't
   you provide a Makefile that works?
A: Note that you need the GNU 'make'. The BSD 'make' won't work, and 
  Solaris 'make' probably won't work either. If you want a better
  configuration and makefile system, write one, then EMAIL me the results --
  mtx is Open Source software and needs your code contributions to grow. 

Q: How do I compile for operating systems other than Linux?
A: MTX no longer needs you to edit the Makefile to compile for operating
   systems other than Linux. Just type ./configure and go with it. 

Q: How do I port it to OS's other than the supported ones?
A: Create a new scsi_ module using one of the existing modules as an
   example (scsi_freebsd.c might be a good model). Decide what symbol
   you want #ifdef'ed in order to include that scsi_ module. Edit
   mtxl.c to #include your scsi_ module. Edit the Makefile to add the
   new target, including the -D needed to #include your new scsi_ module. 

*********************************************************************
Part II: Finding the correct device. 

Q: Why does this command not work??
    [root@Scotty mtxl-1.4.8]# ./mtx -f /dev/st0 inquiry
   In /var/log/messages I see:
      st0: Write not multiple of tape block size. 
A: Note that mtx 1.2 and above use the SCSI GENERIC interface on Linux,
  FreeBSD, and Solaris (at least). They do NOT use the tape device node.

Q: When I do 'mtx -f /dev/sga inquiry' it shows 
      Product Type: Tape Drive
      Vendor Id: HP       
      Product ID: C1553A 
   But when I do a 'mtx -f /dev/sga status' it fails. Why?!
A: You're trying to send a robotics command to a tape drive. You need
   to send robotics commands to robotics devices, not to tape drives. Look in
  /proc/scsi/scsi (Linux) or camcontrol (FreeBSD) to find out what the
  robotics device is. It will be reported as a 'Medium Changer', not a
  'Sequential Access' or 'Tape Drive'.

Q: When I do 'cat /proc/scsi/scsi' it shows only one device, the tape device!
A: You are using a DAT autochanger that has one SCSI ID but two LUN's, LUN 0
   and LUN 1. You need to compile a new kernel with  SCAN SCSI LUNS enabled
   or add this line to your /etc/lilo.conf (then run /sbin/lilo and reboot): 
       append="max_scsi_luns=2"

Q: I'm tired of typing '-f /dev/sgc' all the time. How do I set a default
  device that 'mtx' looks at?
A: Set the CHANGER environment variable. For example, with 'bash':
     export CHANGER=/dev/sgc

Q: I get "modprobe: can't locate module char-major-21"
   syslog messages being squirreled away into a file on our syslog host,
   and mtx doesn't work. What's the problem?
A: You need to compile SCSI generic support into your kernel (or as a module).

Q: When I installed mtx, a message showed 
   up on the console stating that a scsi changer was found at
   dev sgr. However, I have no device /dev/sgr.
A: On Linux, do 'mknod /dev/sgr c 21 19' to create a device node. By default
  only 16 SCSI generic nodes are created, which might not be enough if
  you have multiple SCSI controllers with lots of devices.

******************************************************
III. Operational issues:

Q: I'm using Red Hat 7.0 and mtx works fine when I type ./mtx from the
   command line, but when I use it from scripts I get the following:
    mtx: Request Sense: Error Code=70 (Current)
    mtx: Request Sense: Sense Key=Aborted Command
    mtx: Request Sense: Additional Sense Code = 4E
    mtx: Request Sense: Additional Sense Qualifier = 00
   What's happening?
A: Do "rpm -e mtx". Red Hat 7.0 includes a busted version of mtx. Your
   script is apparently picking up the busted mtx in your path. Get rid
   of the busted mtx, make sure that /usr/local/bin (or wherever you
   put the "good" mtx) is in the path, and all should be well. 

Q: I get
   # /usr/local/bin/mtx -f /dev/sgr status
   mtx: Request Sense: Error Code=70 (Current)
   mtx: Request Sense: Sense Key=Not Ready
   mtx: Request Sense: Additional Sense Code = 04
   mtx: Request Sense: Additional Sense Qualifier = 8E
   mtx: READ ELEMENT STATUS Command Failed
  What gives?
A: Make sure your loader is in random mode, not sequential mode.
   Most "real" loaders (as vs. DAT autoloaders) will not properly report
   status information unless they are in "random" mode. 


Q: I issue 'mtx load 5' and it loads tape 5. But when I try to put the tape
   back in the magazine, we hit problems:
      mtx: MOVE MEDIUM from Element Address 82 to 5 Failed
   What gives?
A: Many loaders require you to first eject the tape (using 'mt' or 'tapectl')
  before you issue an 'unload' command via 'mtx'. 

Q: My Breece Hill loader does not properly report its slots.
A: Either set the "auto-inventory" feature in the loader's control panel, 
   or run 'mtx inventory' prior to running 'mtx status'. 

Q: My Breece Hill loader takes a long time to do an inventory. mtx times
   out and spits all over the place. Help!
A: Many loaders that support barcodes will perform poorly if you place tapes
  into them without bar codes. Place bar codes on all your tapes and you
  should be able to run 'mtx inventory' without that failure.

Q: How do I eject the magazine of my autoloader?
A: Many low-end DAT autoloaders support the removable media 'EJECT' command 
   sent to the robotics device, even though it's not documented (or required)
   in the SCSI standards. If the loader is at /dev/sgb, simply do 
   'mtx -f /dev/sgb eject' and see what happens. (If nothing happens, 
    your autoloader doesn't support 'eject'). Some high-end libraries have 
   their own proprietary way for ejecting magazine trays, generally 
   involving abuse of the 'transfer' command and 'eepos' addendums,
    but this is totally non-standard and undocumented. 

Q: Is there a standard for cleaning tape bar codes?
A: Many libraries, and many backup programs, expect cleaning tape bar 
   codes to start with "CLN". 

Q: How do I report a bug?
A: First, read this FAQ. Next, check the mtx list archives at
   http://mtx.sourceforge.net to make sure that it's not already addressed 
   by somebody else. If your problem is still not solved, send 
   (to the mtx list) the following information:
        Result of 'mtx inquiry' on the loader, 
        Result of 'mtx status' on the loader (minus a bunch of tapes if
          it's a 50+ tape loader!), 
        Results of the operation that isn't working correctly. 

