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Can't open old tape!

Posted on 1998-10-06
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Last Modified: 2013-12-27
I have an 8mm tape that was dumped back in '96.  The system it was dumped on is an Auspex server running Sun OS 4.1.3 at the time(and I'm quite sure it was dumped with the b 126 option).  The server now runs 4.1.4 and some incantation of an auspex bug package.  

For some reason, I'm unable to restore from this tape using restore on that server, ufsrestore on a Solaris 2.3 machine I have or using dd to manually read.  I can query the tape using mt, and I can extract the Table of COntents using tar.
But when I try to initiate an interactive restore it ends up spitting out:

Media Block Size is 20
tape not in dump format.

I know that this tape is(or was) in dump format as we had restored from it before.

Anyone know how I can determine what is wrong here and/or how I may force the output to a different readable block size?

Thanks for any help!
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Question by:bgodden
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Expert Comment

by:ahoffmann
ID: 2007250
can you read anything with tar (-b 126) or dd?
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Author Comment

by:bgodden
ID: 2007251
No I have been unable to use those commands to read the tape, i.e.
tar -xvfb /dev/rxt0 126
or
dd if=/dev/rxt0 bs=126

Both give an I/O error.
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Expert Comment

by:movvam
ID: 2007252
Try using  the tcopy command.
Ex: tcopy /dev/rmt0
It should give some byte information for all formats.

If it does not give any thing then the tape is probly bad.

Regards
Movva
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Author Comment

by:bgodden
ID: 2007253
OK, so it returns:

file1: eof after 0 records: 0 bytes
eot
total length: 0 bytes

Doesn't look good. Can I assume that the tape is hosed?
Thanks,
Brian
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Author Comment

by:bgodden
ID: 2007254
OK, so it returns:

file1: eof after 0 records: 0 bytes
eot
total length: 0 bytes

Doesn't look good. Can I assume that the tape is hosed?
Thanks,
Brian
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Expert Comment

by:movvam
ID: 2007255
Hello Brian,

Definitely i feel that it is bad.

Good Luck !

regards
Movva
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Expert Comment

by:ahoffmann
ID: 2007256
Are you reading from a non-rewinding tape device?
then issue several identical tar commands (ignoring the errors reported).
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Author Comment

by:bgodden
ID: 2007257
Like this?
tar xvf /dev/rmt/0
tar xvf /dev/rmt/0
etc.
etc.
?
..
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Expert Comment

by:ahoffmann
ID: 2007258
Yes.
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Accepted Solution

by:
movvam earned 200 total points
ID: 2007259
As the user dumped the tape way back in 96
and is well familiar with the os commands.


1) See if the tape needs cleaning. If lights on the drive are flashing, it needs cleaning.

2) make sure you have the correct device name for the tape drive.

3) Try the same command in high density mode, ie /dev/rmt/<device#>h to see
 if the tape was written in high density mode.

4) Try to read the tape in another driveand see what happens. If you can read it on another tape drive, then the current drive is hosed.

5) Ultimately, the tape may be bad, or the write was not complete etc.

6) You can always use dd to copy the contents of the tape to disk. Look up the man pages for dd. I'd recommend using large block size so it won't take too long.

Good luck!

Movva
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Author Comment

by:bgodden
ID: 2007260
I apprecited ahoffman's answer as well, although it was unsuccessful and mowam's answer introduced me to a new useful command.
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Expert Comment

by:ahoffmann
ID: 2007261
Would be nice to see the working command here.
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Author Comment

by:bgodden
ID: 2007262
Sorry, my last comment was a bit ambiguous.  Better stated I would say that both folks helped me out here with great suggestions.  mowwam's tcopy command, of which I was not previously aware, revealed that the tape is probably toast.  ahoffman's suggestion was also freat but didn't get me any results (I'm pretty sure I was using a non-rewinding device).  But at any rate, the end result was that my tape is gone and mowwam had helped me first.  To ahoffman:  DId you have some more suggestions or something else I might try here?
Thanks...
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Expert Comment

by:ahoffmann
ID: 2007263
no :(
as mentioned before, if you can't read with dd, you have a problem somewhere (hardware, tape, etc.)
My suggestion about using multiple tar commands is just a workaround for non-rewinding tapes: if you write multiple session with tar, it (tar) is confused while reading and needs an additional try. That's all.
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