Btrfs fs not mounting or being identified after power loss.

Btrfs fs not mounting or being identified after power loss.

[Jordan Windsor]

Hello,
The power to my computer was suddenly cut, one of my btrfs fs (not the
root) has somewhat disappeared, I can't mount it or use any of the
available btrfs tools on it.
Here's some command output:

[root@archpc ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 808.9 GB, 808888614912 bytes, 1579860576 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000db8c9

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              63  1567571967   783785952+  83  Linux
/dev/sdb4      1567571968  1579859967     6144000   82  Linux swap / Solaris


/dev/sdb1 is the lost btrfs fs.

[root@archpc ~]# btrfs-find-root -v /dev/sdb1
No valid Btrfs found on /dev/sdb1

[root@archpc ~]# btrfsck /dev/sdb1
No valid Btrfs found on /dev/sdb1

[root@archpc ~]# mount /dev/sdb1 /mnt/restore/
mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail or so

[ 1767.655429] JBD2: no valid journal superblock found
[ 1767.655432] EXT4-fs (sdb1): error loading journal


If you need anymore information please ask.
Thanks.

Re: Btrfs fs not mounting or being identified after power loss.

[Randy Barlow]

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On 01/08/2013 12:40 AM, Jordan Windsor wrote:
> If you need anymore information please ask.

Kernel and btrfs-tools versions?

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Re: Btrfs fs not mounting or being identified after power loss.

[Jordan Windsor]

Hello,
btrfs-progs is at 91d9eec1ff044394f2b98ee7fcb76713dd33b994
kernel is at 3.6.11-1-ARCH
Thanks.

On Wed, Jan 9, 2013 at 10:01 AM, Randy Barlow
<randy@electronsweatshop.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 01/08/2013 12:40 AM, Jordan Windsor wrote:
>> If you need anymore information please ask.
>
> Kernel and btrfs-tools versions?
>
> - --
> R
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> Version: GnuPG v2.0.19 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>
> iEYEARECAAYFAlDsrFwACgkQw3vjPfF7QfWLUgCdFiJE4zTHeG3rxqlojSZ+Qid3
> +CEAoInZeeawLa9Blh7/bYhXx0LK++sa
> =oJtF
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Re: Btrfs fs not mounting or being identified after power loss.

[David Sterba]

On Tue, Jan 08, 2013 at 04:10:13PM +1030, Jordan Windsor wrote:
> /dev/sdb1 is the lost btrfs fs.
> 
> [root@archpc ~]# btrfs-find-root -v /dev/sdb1
> No valid Btrfs found on /dev/sdb1

> [root@archpc ~]# btrfsck /dev/sdb1
> No valid Btrfs found on /dev/sdb1

Looks like the first superblock is partially or completely damaged.
Btrfsck is able to operate starting from a different superblock

  btrfsck --super 1 /dev/sdb1

to see if there are other valid copies.

david

Re: Btrfs fs not mounting or being identified after power loss.

[Jordan Windsor]

Hello,
here's the output:

[root@archpc btrfs-progs]# ./btrfsck --super 1 /dev/sdb1
using SB copy 1, bytenr 67108864
No valid Btrfs found on /dev/sdb1

Thanks.

On Wed, Jan 9, 2013 at 11:29 PM, David Sterba <dsterba@suse.cz> wrote:
> On Tue, Jan 08, 2013 at 04:10:13PM +1030, Jordan Windsor wrote:
>> /dev/sdb1 is the lost btrfs fs.
>>
>> [root@archpc ~]# btrfs-find-root -v /dev/sdb1
>> No valid Btrfs found on /dev/sdb1
>
>> [root@archpc ~]# btrfsck /dev/sdb1
>> No valid Btrfs found on /dev/sdb1
>
> Looks like the first superblock is partially or completely damaged.
> Btrfsck is able to operate starting from a different superblock
>
>   btrfsck --super 1 /dev/sdb1
>
> to see if there are other valid copies.
>
> david

Re: Btrfs fs not mounting or being identified after power loss.

[Randy Barlow]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 01/08/2013 10:46 PM, Jordan Windsor wrote:
> kernel is at 3.6.11-1-ARCH

Sorry I don't know much to help you, but I would suggest perhaps using
a newer kernel in the future. It sounds like your FS might be in
trouble as is, but I would recommend using the most recent RC kernel
(3.8-rc3) and restoring your data to a new btrfs from backups. In
general, it's a good idea to stick to pretty recent kernels with btrfs.
Hope this helps!

- -- 
R
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Re: Btrfs fs not mounting or being identified after power loss.

[David Sterba]

On Thu, Jan 10, 2013 at 01:27:33AM +1030, Jordan Windsor wrote:
> [root@archpc btrfs-progs]# ./btrfsck --super 1 /dev/sdb1
> using SB copy 1, bytenr 67108864
> No valid Btrfs found on /dev/sdb1

Please dump the existing superblocks to files and send them to me (they
do not contain any sensitive information) with commands

dd if=/dev/sdb1 bs=1k count=4 skip=64 of=sdb1-sb0
dd if=/dev/sdb1 bs=1k count=4 skip=65536 of=sdb1-sb1

to see if the data at least resemble a superblock.


david

Re: Btrfs fs not mounting or being identified after power loss.

[David Sterba]

On Wed, Jan 09, 2013 at 10:43:24PM -0500, Randy Barlow wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> > kernel is at 3.6.11-1-ARCH
> 
> Sorry I don't know much to help you, but I would suggest perhaps using
> a newer kernel in the future. It sounds like your FS might be in
> trouble as is, but I would recommend using the most recent RC kernel
> (3.8-rc3) and restoring your data to a new btrfs from backups. In
> general, it's a good idea to stick to pretty recent kernels with btrfs.

There are some problems with the 3.8-rc kernels, please do not use them
yet, and I don't think that kernel upgrade would help in Jordan's case.

david

Re: Btrfs fs not mounting or being identified after power loss.

[Jordan Windsor]

Hello,
I've already recreated btrfs on the partition, so there'd be nothing
useful to send.
Thanks.

On Thu, Jan 10, 2013 at 10:13 PM, David Sterba <dsterba@suse.cz> wrote:
> On Wed, Jan 09, 2013 at 10:43:24PM -0500, Randy Barlow wrote:
>> -----BEGIN PGP SIGNED MESSAGE-----
>> > kernel is at 3.6.11-1-ARCH
>>
>> Sorry I don't know much to help you, but I would suggest perhaps using
>> a newer kernel in the future. It sounds like your FS might be in
>> trouble as is, but I would recommend using the most recent RC kernel
>> (3.8-rc3) and restoring your data to a new btrfs from backups. In
>> general, it's a good idea to stick to pretty recent kernels with btrfs.
>
> There are some problems with the 3.8-rc kernels, please do not use them
> yet, and I don't think that kernel upgrade would help in Jordan's case.
>
> david
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