Re: [Networker] How fabricate (disk) volume label

2005-04-29 09:31:07
Subject: Re: [Networker] How fabricate (disk) volume label
From: "Harald A. Irmer" <Harald.Irmer AT ATIS.UNI-KARLSRUHE DOT DE>
Date: Fri, 29 Apr 2005 15:25:05 +0200

I got the problem solved - Hexeditor is your friend!

Steps: (Networker 6.1.4 for UNIX)
1. Copy a similar "volume" file from another file system, i.e. if you want to restore the label of I-206 use as sample file a copy of the volume file of I-306.
2. Get the volume ID needed:
bash-2.03# mminfo -a -r'volid' I-206

Translate into Hex 742714369 -> 2C 44 EC 01
pattern:                                          NN NN NN 01
Get and translate into Hex also the volid of the sample, I-306, 2717896961 -> A1 FF D1 01 pattern: MM MM MM 01
3. Search with the hex editor the file /nsr/mm/mmvolume6/vol.0 for the
pattern 2C 44 EC
You will find e.g.
&237584: 2C 44 EC 01 42 2C 44 EC 0A 00
pattern:     NN NN NN 01 XX NN NN NN II II
&237600: 2C 44 EC
pattern:      NN NN NN
&237680: 42 2C 44 EC
pattern:      XX NN NN NN

(you compute NN NN NN but you cannot guess the value of II  II  and  XX)

The corresponding entries in the sample file (volume file of I-306)
&32900: A1 FF D1 01 41 A1 FF D1 00 08
pattern:    MM MM MM 01 YY MM MM MM JJ JJ
&32972: 41 A1 FF D1
pattern:   YY MM MM MM
&32992: A1 FF D1 01 41 A1 FF D1 00 08
pattern:    MM MM MM 01 YY MM MM MM JJ JJ

overwrite in the sample file M by N, Y by X, J by I and the string I-306 by I-206 and you have reconstructed the lost I-206 volume file. It works! I tested first in a test disk file to which I copied the new "volume" file and a saveset from I-206. The test is "scanner -v <Test device>".
An analogue method should apply to overwritten tapes if the volume entry
in vol.0 is still present.
Lately I solved the problem of a broken disk file, all  in lost+found:
fgrep -l "<volume string> /lost+found/\#*  ->  "volume" file found.

With "volume" file in / copy one after another (make perl script) /lost+found/\#* to /1000000000.0
"scanner  -v  <Test device>" says: Expected 1234567890.0 found 1000000000.0
So you have detected 1234567890.0 ...

Use test device before. No warranties. You are on your own risk.


Harald A. Irmer
ATIS - Abteilung Technische Infrastruktur

University of Karlsruhe        Email: Harald.Irmer AT atis.uni-karlsruhe DOT de
Faculty of Computer Science    WWW  :
Building 50.34 Room-No. 009
Am Fasanengarten 5         Fon  : +49 (721) 608-6963
D-76131 Karlsruhe / Germany     Fax  : +49 (721) 608-6699

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