Summary: Recovery from an overwritten tape

From: Connolly, Michael (
Date: Tue Feb 29 2000 - 19:52:57 CST


As expected I can't do what I want to do (safely). I know about the mt
command and of course positioned the tape to the end of the second tar file.
What I wanted to do was (somehow) skip through to the beginning of the NEXT
tar file but due to the way tar works it places and EOT marker at the end of
the second tar file and Solaris has no way of getting past that EOT.

One reply was to use dd after getting to the end of the second tar file but
I kept getting I/O errors.

Most suggested going to a data recovery company as they would have the tools
to get beyond that EOT.

A couple mentioned the following but it didn't look safe or successful:

"Some in the past have attempted to write data over the EOT mark.
Then during the write, power off the drive. This leaves the data
confused, but without an EOT. You *may* have some luck forwarding over
the bad data and into the "old" data stream. Most individuals that have
tried this did not report success."

Thanks to:

Arthur Dunham
Jeff Kennedy
David Foster
Birger Wathne
Richard Bond
Anthony David
David Evans

Michael J. Connolly
CAD/CAE/PDM Systems Administrator
C&K Components, Inc.

        Original post:

> Greetings,
> I have just discovered that my incremental backup rewound itself (after a
> power failure) and wrote two nights tar files to a tape that contained
> approximately 20 tar files. This shouldn't have happened as the backup
> routine counts a number of list files and does an mt command to move the
> tape forward n number of list. It then begin a new increment backup. I am
> still mystified as the backup command is from an nfs mount which (due to
> the
> power failure) was not mounted at the time.
> Anyway, is there a way to get to the beginning of the next tar file after
> the first two. In other words is it possible to skip over the first two
> and
> get to the next available beginning of tar file? If this isn't clear pleas
> e-mail direct and I will elaborate.
> Regards,
> Michael J. Connolly
> CAD/CAE/PDM Systems Administrator
> C&K Components, Inc.

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