Recovering 4mm tar tapes
pete at dunnington.plus.com
Mon Sep 12 17:05:52 CDT 2016
On 12/09/2016 16:12, Douglas Taylor wrote:
> I have a pair of 4mm DDS tapes from 1999 that I would like to recover.
> I was able to read one with tar on a Debian (jessie) Linux system, but
> the second gives an error.
> The second tape is a 3M brand with DDS markings and 4 bars next to the
> DDS logo. It also has 'Media Recognition System' and DD-90 written on
> it. Here is the dialog and error:
> root at T5400deb:/home/taylor/4mm_tar_1998# tar -xvf /dev/st0
> tar: /dev/st0: Cannot read: Input/output error
> tar: At beginning of tape, quitting now
> tar: Error is not recoverable: exiting now
> (None of the config jumpers were installed for the tape that I could
> read) Is the 2nd tape just bad and can't be read? Or do I need a
> slightly different tape drive?
It could be corrupt, or it could be byte-swapped, or it could have a
strange block size (especially a small one), or the heads might need
cleaned after reading the last tape, or it might not have any valid
data. Does the debian tape driver support byte-swapping? Or is there a
bs and non-bs version? You could try reading it with something like
dd if=/dev/rmt/tapedevice bs=20b conv=swab | tar tvf -
or whatever the debian tape device equivalent is. Does debian have some
equivalent to mt(1) to read/set the drive's blocksize and to move
forward and back along the tape?
Personally I hate DDS/DDS2/DDS3. I always had better luck with half
inch and even 8mm, and better still with DLT.
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