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KevinB AT paccessglobal DOT com wrote:
> 
> I believe you would also want write a script that dd'ed a bit pattern over
> the tape.  The question is, which is going to be slower, the dd process or
> the degauss/relabel process.  From an automation perspective I think the
> relabel overwrite method would be easier to implement.  If the risk of data
> theft from backup tapes is that critical then perhaps the cost of several
> new drives for this would be justified.
> 

As a result of a previous post I made to this list on a similar DLT tape
issue, I had concocted this script for overwriting the header file.  The
process is somewhat slow, maybe 3 minutes per tape, but not too bad--and
it beats having your hands go numb from using the degausser.  My problem
was that we were going to a new tape labeling convention, and we had put
new physical labels on tapes without erasing them.  What we got were
tapes with a new tapes label as its EVSN, and the old media ID as its
RVSN.  I use it now to erase a large amount of tapes by giving the
script name plus a list of tapes I want to erase, like this:

# tpidclr TAPE1 TAPE2 TAPE3 TAPE4

Just be careful to put the right media IDs!  I tried unsuccessfully to
get it to force a tape to be in a specific pool (like 'None') before it
would allow erasing, so as not to erase tapes in other pools by
accident.  As it is, I just stage them in the None pool so that no
backups will take them while they are being erased.  I suppose you could
also use the functionality of this script to be more automated.

Hope this helps.


Regards,

Ryan
--
Ryan C. Anderson        |   United Defense L.P.    
Unix Administrator      |   763.572.6684 (desk)
ryan_anderson AT udlp DOT com  |   612.235.9936 (pager)
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#!/bin/sh
#
# File: tpidclr
# Author: Ryan Anderson (from Blayne Puklich)
# Creation date: 2000-09-11
# Time-stamp: " "
#
# Description
#   Clear a tape media id (RVSN) by zeroing out the first part
#   of the media.  Clears EVSNs passed as parameters; if there
#   are no parameters reads STDIN.
#
# $Log$
#

PATH=/usr/openv/netbackup/bin/admincmd:/usr/openv/netbackup/bin
PATH=$PATH:/usr/openv/volmgr/bin:/usr/local/bin:/usr/sbin:/usr/bin
export PATH

gMe=`basename $0 .sh`

#
# Clear the RVSN given to us.
clear_tape() # media_id
{
        tpreq -ev $1 -d dlt -f /tmp/$1
        dd if=/dev/zero of=/tmp/$1 bs=512 count=20
        tpunmount /tmp/$1
        rm -f /tmp/$1
        echo "DLT with barcode $1 header erased"
}

if [ $# -gt 0 ]; then
    #
    # Clear all tapes passed on command line
    for evsn in $*; do
        clear_tape $evsn
    done
else
    #
    # Clear all tapes passed on stdin
    while read evsn; do
        clear_tape $evsn
    done
fi
exit 0

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