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Date:      Sun, 10 Dec 2006 15:27:56 +0900
From:      FK <fk@zepher.dyndns.org>
To:        perryh@pluto.rain.com
Cc:        fk@zepher.dyndns.org, freebsd-questions@freebsd.org
Subject:   Re: How can I fix "Cannot find file system superblock" problem?
Message-ID:  <20061210152756J.fk@zepher.dyndns.org>
In-Reply-To: <457b3f3a.e4Sf%2BYRQsI6sLl6z%perryh@pluto.rain.com>
References:  <20061210061828K.fk@zepher.dyndns.org> <457b3f3a.e4Sf%2BYRQsI6sLl6z%perryh@pluto.rain.com>

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Dear all members,

From: perryh@pluto.rain.com
Subject: Re: How can I fix "Cannot find file system superblock" problem?
Date: Sat, 09 Dec 2006 14:56:58 -0800
Message-ID: <457b3f3a.e4Sf+YRQsI6sLl6z%perryh@pluto.rain.com>

perryh> > #diff -s sb1 sb2
perryh> > Files sb1 and sb2 are identical
perryh> > #diff -s sb1 sb3
perryh> > Files sb1 and sb3 are identical
perryh> 
perryh> It might be worthwhile to check one of these identical "alternates"
perryh> against the "real" superblock.  (AFAIK only the first 512 bytes, or
perryh> less, actually matter.)  You might also post a dump of the first 512
perryh> bytes and see if anyone notices anything.

Thank you for your reply. 
Following your suggestions, I tried these.

#dd if=/dev/da0s2a skip=0 bs=512 count=16 of=sb0
16+0 records in
16+0 records out
8192 bytes transferred in 0.011918 secs (687360 bytes/sec)

#diff -s sb0 sb1
Binary files sb0 and sb1 differ

Dump for the master superblock (the first 512 bytes only).
#od -x sb0
0000000      d440    10fa    9b10    09e1    9524    7b55    f334    153f
0000020      f190    0b4a    387c    5d46    1b94    14b0    ae10    0b19
0000040      4e3c    b446    b870    138f    7190    0ab7    ff52    75e6
0000060      5dac    130e    bbf0    0a8a    0000    0000    0000    0000
0000100      0000    0000    0000    0000    0000    0000    0000    0000
0000120      1d12    7b57    1a88    113f    d610    0a84    a2be    064f
0000140      7eb8    1226    3290    0a44    9e3c    7b57    f870    0f9e
0000160      cb00    0932    cad0    7b57    1764    13e4    31d0    0ad4
0000200      0000    0000    0000    0000    0000    0000    4bfa    7b58
0000220      f54c    1243    41e0    0a4e    f1a6    41f0    d97c    13ef
0000240      eb00    0ad7    cd24    7b58    d334    10a3    66d0    09c8
0000260      be3c    6d39    7870    15ab    d1b0    0b6f    52be    7b59
0000300      3eb8    0fe3    4600    0973    0000    0000    0000    0000
0000320      0000    0000    0000    0000    0000    0000    0000    0000
0000340      007c    7b5a    3b94    1288    2820    0a65    f890    3fda
0000360      1440    15e3    b780    0b82    81a6    7b5a    197c    10e8
0000400      ed10    09da    0000    0000    0000    0000    0000    0000
0000420      2f66    7b5b    1658    138d    ed60    0ab5    0000    0000
0000440      0000    0000    0000    0000    b090    7b5b    f440    11ec
0000460      2d70    0a30    0000    0000    0000    0000    0000    0000
0000500      31ba    7b5c    d228    104c    cff0    09ad    5e4e    7b5c
0000520      f11c    1491    98e0    0b0f    ff52    78a4    5dac    11c6
0000540      18f0    0a23    e3e8    7b5c    5ca0    13d1    c3d0    0acd
0000560      0000    0000    0000    0000    0000    0000    6512    7b5d
0000600      3a88    1231    d3e0    0a47    0000    0000    0000    0000
0000620      0000    0000    e63c    7b5d    1870    1091    a8d0    09c1
0000640      9abe    514e    5eb8    1471    9230    0b04    0000    0000
0000660      0000    0000    0000    0000    93fa    7b5e    154c    1336
0000700      5920    0a98    2ae4    26ef    9010    14b5    c730    0b1b
0000720      1524    7b5f    f334    1195    8930    0a12    41ba    7b5f
0000740      1228    15db    daa0    0b7f    9abe    7b5f    5eb8    10d5
0000760      8f10    09d4    c2e4    7b5f    f010    143a    d4a0    0af1

Dump for one of alternative superblock (the first 512 bytes only).
#od -x sb1
0000000      0000    0000    0000    0000    0028    0000    0030    0000
0000020      0038    0000    0bb8    0000    0000    0000    0000    0000
0000040      0000    0000    0000    0000    0000    0000    0033    0000
0000060      4000    0000    0800    0000    0008    0000    0008    0000
0000100      0000    0000    0000    0000    c000    ffff    f800    ffff
0000120      000e    0000    000b    0000    0008    0000    0800    0000
0000140      0003    0000    0002    0000    0800    0000    0000    0000
0000160      0000    0000    0800    0000    0040    0000    0000    0000
0000200      0000    0000    0000    0000    0000    0000    0000    0000
0000220      bf56    444b    a5bf    c858    0000    0000    0800    0000
0000240      4000    0000    0000    0000    0000    0000    0000    0000
0000260      0000    0000    0000    0000    5c00    0000    6f88    0001
0000300      0000    0000    0000    0000    0000    0000    0000    0000
0000320      0100    8000    0000    0000    0000    0000    0000    0000
0000340      0000    0000    0000    0000    0000    0000    0000    0000
*
0001520      0000    0000    0000    0000    0000    0000    4000    0000


Does my superblock have anything wrong?

This dump analysis is beyond my tecknical knowledge.
So Thanks a lot for your help!

--
FK.



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