Debian bug report logs - #746
mt doesn't support setblk (and other options)

Message received at debian-bugs:

From cus.cam.ac.uk!iwj10 Sat Jun 17 06:27:02 1995
Return-Path: <iwj10@cus.cam.ac.uk>
Received: from pixar.com by mongo.pixar.com with smtp
	(Smail3.1.28.1 #15) id m0sMxtt-0007mPC; Sat, 17 Jun 95 06:27 PDT
Received: from bootes.cus.cam.ac.uk by pixar.com with SMTP id AA25691
  (5.67b/IDA-1.5 for debian-bugs-pipe@mongo.pixar.com); Sat, 17 Jun 1995 06:25:31 -0700
Received: by bootes.cus.cam.ac.uk 
	(Smail-3.1.29.0 #36) id m0sMxtm-000BzuC; Sat, 17 Jun 95 14:26 BST
Received: by chiark
	id <m0sMwzz-0000XqZ@chiark.al.cl.cam.ac.uk>
	(Debian /\oo/\ Smail3.1.29.1 #29.32); Sat, 17 Jun 95 13:29 BST
Message-Id: <m0sMwzz-0000XqZ@chiark.al.cl.cam.ac.uk>
Date: Sat, 17 Jun 95 13:29 BST
From: iwj10@cus.cam.ac.uk (Ian Jackson)
To: Debian bugs submission address <debian-bugs@pixar.com>
Subject: Re: Bug#746: mt doesn't support setblk (and other options)
In-Reply-To: <m0rwEoe-0007akC@grus.cus.cam.ac.uk>
References: <m0rvz4k-0000YSZ.ijackson@nyx.cs.du.edu>
	<m0rwEoe-0007akC@grus.cus.cam.ac.uk>

I complained that the version of `mt' we are distributing doesn't
support `setblk' and various other options.

I've just read the attached message in col.hardware.  Clearly we
should be distributing a different version of `mt'.

Ian.

Newsgroups: comp.os.linux.hardware
Message-ID: <3q4fgr$sg@annex-1-slip-jik.cam.ov.com>
References: <3q3mr6$hir@azure.acsu.buffalo.edu>
NNTP-Posting-Host: annex-1-slip-jik.cam.ov.com
From: jik@annex-1-slip-jik.cam.ov.com (Jonathan Kamens)
Subject: Re: 4mm DAT tape R/W on PC and SGI problem
Date: 26 May 1995 11:54:03 GMT

Your question is answered in the SCSI HOWTO.  Go read it.  In particular:

Section 6.2.4 :  Problems taking tapes to/from other systems.

	You can't read a tape made with another operating system or
	another operating system can't read a tape written in Linux.

	Different systems often use different block sizes.  On a
	tape device using a fixed blocksize, you will get errors 
	when reading blocks written using a different block size.

	To read these tapes, you must set the blocksize of 
	the tape driver to match the blocksize used when
	the tape was written, or to variable.

	NOTE : this is the hardware block size, not the blocking
	factor used with tar, dump, etc.

	You can do this with the mt command - 

	
		mt setblk <size>

	or 
	
		mt setblk 0

	to get variable block length support.

	Note that these mt flags are NOT supported under the GNU version
	of mt which is included with some Linux distributions.  Instead,
	you must use the BSD derrived Linux SCSI mt command.  Source
	should be available from

	tsx-11.mit.edu:/pub/linux/ALPHA/scsi

Message received at debian-bugs:

From cus.cam.ac.uk!iwj10 Tue Apr  4 12:45:35 1995
Return-Path: <iwj10@cus.cam.ac.uk>
Received: from pixar.com by mongo.pixar.com with smtp
	(Smail3.1.28.1 #15) id m0rwEXe-0006EfC; Tue, 4 Apr 95 12:45 PDT
Received: from bootes.cus.cam.ac.uk by pixar.com with SMTP id AA00875
  (5.65c/IDA-1.4.4 for <debian-bugs@pixar.com>); Tue, 4 Apr 1995 12:43:30 -0700
Received: by bootes.cus.cam.ac.uk 
	(Smail-3.1.29.0 #30) id m0rw96z-000C0wC; Tue, 4 Apr 95 14:57 BST
Received: by chiark
	id m0rvz4k-0000YSZ
	(Debian /\oo/\ Smail3.1.29.1 #29.27); Tue, 4 Apr 95 04:14 BST
Message-Id: <m0rvz4k-0000YSZ.ijackson@nyx.cs.du.edu>
Date: Tue, 4 Apr 95 04:14 BST
From: iwj10@cus.cam.ac.uk (Ian Jackson)
To: Debian bugs submission address <debian-bugs@pixar.com>
Subject: mt doesn't support setblk (and other options)

Package: cpio
Version: 2.3-2

Here is an edited unidiff between the manpage for setblk on my old
installation and that from Debian 0.93R5 (+ indicates an option or
meaning that's in Debian, - indicates an option or meaning that's in
my old program).

The manpage for each program appears to describe its behaviour
reasonably accurately for the operations I have used; however, I
rarely use `fsf' and similar operations.

I need some of the missing options - in particular, I need setblk, and
others may need setdensity.  seek and tell would also be quite useful.

BTW, the similarities in the wording suggest that at least the two
manpages have a common origin.

I have the source code for my `mt' program; it is from `tape-dist',
which at one point came with the kernel SCSI tape driver.  The README
is dated November 1992.  According to the README:

  The tape control program in this package is mt from the BSD NET2-release
  with the following additions: the commands erase, setblk, and setdensity
  have been added. setblk takes one argument which is the block size for the
  subsequent tape requests.   ...

I shall upload a tarfile (tape-dist-containing-mt.tar) to Incoming.

Ian.

        weof
+       eof
              Write count EOF marks at current position.
 
        fsf    Forward space count files.  The tape is  positioned
              on the first block of the next file.
 
-       fsfm   Forward  space count files.  The tape is positioned
-             on the last block of the previous file.

        bsf    Backward space count files.  The tape is positioned
+             on the first block of the next file.
-             on the last block of the previous file.

-       bsfm   Backward space count files.  The tape is positioned
-             on the first block of the next file.
 
+       bsfm   Backward space count file marks. The tape is posi-
+             tioned  on  the  beginning-of-the-tape  side of the
+             file mark.
 
+       asf    Absolute space to file number count.  Equivalent to
+             rewind followed by fsf count.
 
+       eom    Space  to the end of the recorded media on the tape
+             (for appending files onto tapes).
 
-       eod, seod
-             Space to end of valid data.  Used on streamer  tape
-             drives to append data to the logical and of tape.
 
-       setblk Set  the block size of the drive to count bytes per
-             record.
 
-       setdensity
-             Set the tape density code to  count.   The  proper
-             codes  to use  with each drive should be looked up
-             from the drive documentation.
-
-       seek   Seek to the count block on the tape.   This  opera-
-             tion  is  available  on  some  Tandberg and Wangtek
-             streamers and some SCSI-2 tape drives.
-
-       tell   Tell the current block on tape.  This operation  is
-             available on  some  Tandberg and Wangtek streamers
-             and some SCSI-2 tape drives.