SUMMARY: ufsrestore on a 8 year old sun4 dump tape

From: Doty, Randall W <>
Date: Thu May 22 2003 - 17:04:11 EDT

Thanks to all who responded with your suggestions.  Many of you suggested
using dd which I had previously tried but the results were unfruitful.  I
believe I have a tape that can not be read with my drive and version of o/s as
some of you suggested.

I found another tape with the data sought and Darren Dunham of Taos - The
SysAdmin Company hit my solution needed.  Darren provided me some insight on
how to determine what command wrote the tape records by analyzing the dd
output in octal.

Darren wrote:

    Ignore the format and see if you can read anything at all useful from

    Does this get anything?

    % mt -f /dev/rmt/0n rewind
    % dd if=/dev/rmt/0n of=/tmp/data bs=64k count=2

    If it does, show me this..

    % od -c /tmp/data | head

This resulted:

  0000000  \0  \0  \0 001   7 263  \n 261  \0  \0  \0  \0  \0  \0  \0 001
  0000020  \0  \0  \0  \0  \0 017 204 377  \0  \0 352   l       e 346 327
  0000040  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0

Darren continues:

Gotcha.  That's definitely a UFS dump tape.  The \0 \0 352  l beginning at
position 24 is indicative of ufsdump.  Now that you can read the
bits, lets see if we can get restore to recognize it.  Try this..

(rewind tape)
dd if=/dev/rmt/0n ibs=64k | ufsrestore if -

If you get a restore> prompt, you can do a 'ls' and 'cd' to look around
at the data that should be on the tape.

Larye D. Parkins suggested that the tape maybe deteriorated beyond recovery.

Larye wrote: Even with semi-modern technology, magnetic tape is ephemera: the
shelf-life of a tape is probably about two years, maybe less (my hunch/guess
based on 40+ years of industry experience with computer and audio tapes).  The
problem is the same magnetic characteristics that make it possible to write on
the tape in the first place doom it to a certain half-life, as the magnetic
domains on the tape gradually randomize themselves.  The adhesive matrix that
bonds the magnetic particles onto the substrate (plastic tape) also has a
shelf-life.  One of the big problems with older tapes is loose oxide, which is
most certainly randomly oriented once it flakes off the tape:

try cleaning the tape, if you have a tape cleaner (they used to make them for
reel-to-reel tapes, but I haven't ever seen one for cartridges: the drives may
have cleaning blades built-in) or fast-forward to end-of-tape, rewind, eject,
then clean the drive, try to read the tape, repeat up to three times.

But, with an eight-year-old tape, it is possible that the domains have just
faded out so the signal level is too low to read.  Those old Exabyte 8-tracks
were also very adjustment-sensitive: it wasn't uncommon to have a drive that
could read tapes it had written, but the tapes couldn't be read on any other
[otherwise identical] drive.  In the really bad old days of reel-to-reel tape,
I remember at least once using the tape we were trying to recover as an
alignment tape to misadjust the drive we were using to match the one it had
been written on.


Thanks all for your quick replies

Hi all,

I have a 1995 8mm 112M tape I am assured it is a dump tape.  I have no other
details.  I assume it was written on a Sun4OS.  I have had no luck reading
this tape on my Exabyte EXB-8500 installed on my Solaris9 Ultra 10.  The
response to all that I have tried is:

ufsrestore ibf 126 /dev/rmt/0n
 Read error while trying to set up volume
 Continue? [yn] y
 Volume is not in dump format

Any ideas?

Also I have a tar format 8mm tape of the same data set but that has not
readable either.

         Randy Doty

BOEING IT UNIX Administrator
*Phone:  (253) 773-9419
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Received on Thu May 22 17:04:05 2003

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