SUMMARY: how to recover overwritten tarfiles

From: Martin Achilli (ACHILLM@IMIHSRA.BITNET)
Date: Tue Feb 01 1994 - 04:48:44 CST


Hello,
      the problem I posted was that of one of our users having overwritten the
7th tar file on a tape which contained 20 or more. I wanted to recover whatever
 possible after tar file number 7.

system: sparcstation 2 with 4.1.3
drive: procom 2Gb DAT drive, no modifications to /sys/scsi/targets/st_conf.c
tar files: average size 40Mb each

I received 12 replies, 6 suggested to move to tar file number 8 by using
mt -f /dev/nrst1 fsf 8
unfortunately this does NOT work, the mt command is not smart enough to figure
out that it must skip the remains of the previously written tar file and move o
nto the next.

The other replies suggested that I should move to the end of tar file number 7,
 start writing a new tar file and, when I was confident that the EOM marker of
the remains of the previously written tar file had been passed, flip the power
switch on the drive.
This makes sense, but unfortunately it did not work for me.
I used mt to move to tar file 8 9 10 etc.. but when the tape rea
ches the point where you flipped the power switch it starts clicking repeatedl
y as if the error correction circuitry is trying to recover data. You then rece
ive an I/O error, and mt stops.

If anyone has further suggestions I would be grateful.
Thanks to:
Richard J. Niziak, Mark Becker, James Ashton, Piete Brooks, Dave Fetrow, Larry
Chin, Ian Camm, Paul Cushing, cwaters at navy.mil, Dan Stromberg, Risto Tolonen
, Todd Leroy.

Martin



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