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Re: ext3 crash





From: Andreas Dilger <adilger clusterfs com>
To: Andy Paul <aaspaul hotmail com>
CC: ext3-users redhat com
Subject: Re: ext3 crash
Date: Mon, 8 Apr 2002 02:23:17 -0600

On Apr 08, 2002 15:08 +0900, Andy Paul wrote:
> - I suppose I can survive without it. Would have used RAID, had I needed an
> insurance policy. I am more concerned about not finding the cause and
> having the same experience repeated next time.


Well, RAID is not a form of backup, especially in a case like this.  It
only protects you from disk failures, not software screw-ups.

> - The error sequence started when a user tried to access some data using
> samba. Noticing some strange delay, he cancelled the request, however samba
> (?) seemed to have entered some retry loop, trying to access various
> inodes/blocks for about 1 hour, and filling the log with errors.


Sounds like a software problem to me.

> #od -Ax -tx4 /dev/hda9
> 000200 9a038c08 9476785f 49bf458f c00096e3
>      :     :        :        :        :
> 0003f0 d9995854 d6aaaddf 04b01455 41407ffe

This chunk is repeated every few sectors on your disk.  This is why I
think it looks like a software problem.

> 000400 00664000 00cc7892 000a393a 00267129
> 000410 00662dfc 00000000 00000002 00000002
> 000420 00008000 00008000 00004000 3ca7c82d
> 000430 3cb11525 00250019 0003ef53 00000001
> 000440 3c05b658 00ed4e00 00000000 00000001
> 000450 00000000 0000000b 00000080 00000004
> 000460 00000002 00000001 a73c96f6 d34646c9
> 000470 8258dcb3 d03f0f27 6168732f 00366572

This seems like a normal superblock (probably written out later over the
rest of the junk on the disk).

> 000800 9a038c08 9476785f 49bf458f c00096e3
>      :     :        :        :        :
> 0009f0 d9995854 d6aaaddf 04b01455 41407ffe
> 000a00 9a038c08 9476785f 49bf458f c00096e3
>      :     :        :        :        :
> 000bf0 d9995854 d6aaaddf 04b01455 41407ffe
> 000c00 9a038c08 9476785f 49bf458f c00096e3
>      :     :        :        :        :
> 000e00 9a038c08 9476785f 49bf458f c00096e3
>      :     :        :        :        :
> 000ff0 d9995854 d6aaaddf 04b01455 41407ffe

> #./findsuper /dev/hda9 512 0
> starting at 0, with 512 byte increments
>       thisoff     block fs_blk_sz  blksz grp last_mount
>          1024         1  13400210  4096    0 Mon Apr  1 11:38:37 2002

Normal superblock...

>       8053760      7865  13400210  4096    0 Mon Apr  1 11:38:37 2002
>             :         :      :        :    :  :   :   :   :  :     :
>       8082432      7893  13400210  4096    0 Mon Apr  1 11:38:37 2002

Superblocks in the journal...

>     134217728    131072  13400210  4096    1 Mon Apr  1 11:38:37 2002
>     402653184    393216  13400210  4096    3 Mon Apr  1 11:38:37 2002
>     671088640    655360  13400210  4096    5 Mon Apr  1 11:38:37 2002
>     939524096    917504  13400210  4096    7 Mon Apr  1 11:38:37 2002
>    1207959552   1179648  13400210  4096    9 Mon Apr  1 11:38:37 2002
>    3355443200   3276800  13400210  4096   25 Mon Apr  1 11:38:37 2002
>    3623878656   3538944  13400210  4096   27 Mon Apr  1 11:38:37 2002
>    6576668672   6422528  13400210  4096   49 Mon Apr  1 11:38:37 2002
>   10871635968  10616832  13400210  4096   81 Mon Apr  1 11:38:37 2002

Backup superblocks. ^^^^ Try using some of these numbers for e2fsck,

e2fsck -b 131072 /dev/hda9
e2fsck -b 393216 /dev/hda9
e2fsck -b 917504 /dev/hda9
:


e2fsck produced the following output :


---------
# e2fsck -b 131072 /dev/hda9
e2fsck 1.26 (3-Feb-2002)
e2fsck: Bad magic number in super-block while trying to open /dev/hda9

The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
   e2fsck -b 8193 <device>

# e2fsck -b 393216 /dev/hda9
e2fsck 1.26 (3-Feb-2002)
e2fsck: Bad magic number in super-block while trying to open /dev/hda9

The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
   e2fsck -b 8193 <device>

# e2fsck -b 10616832 /dev/hda9
e2fsck 1.26 (3-Feb-2002)
e2fsck: Attempt to read block from filesystem resulted in short read while trying to open /dev/hda9
Could this be a zero-length partition?


# e2fsck -b 6422528 /dev/hda9
e2fsck 1.26 (3-Feb-2002)
e2fsck: Bad magic number in super-block while trying to open /dev/hda9

The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
   e2fsck -b 8193 <device>

-----------

I think I would like to stop at this point, due to lack of time ( and patience). I will reformat the partition tomorrow.

Andreas, thank you for your time.

Adrian


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