read-only drive with reiserfs partiton not mountable

read-only drive with reiserfs partiton not mountable

[Joel Ebel]

Ok.  I've got an unusual problem.  My hard drive decided yesterday to 
turn read-only.  I can't write anything to it.  The data seems to be all 
  there and readable, but any write to the drive fails.  I have 
partitions of NTFS, FAT32, ext3, and reiserfs.  I'm able to mount all 
the other partitions and copy files off of them, but the reiserfs 
partition refuses to mount saying wrong fs type, bad superblock, etc... 
  Is there a reason that a reiserfs partition on a read-only drive 
wouldn't mount?  I'd sure like to get what data I can off of it.  Any ideas?

Thanks,
Joel Ebel

Re: read-only drive with reiserfs partiton not mountable

[Carl-Daniel Hailfinger]

[Sorry, I hit send a bit too early]
Carl-Daniel Hailfinger wrote:
> Joel Ebel wrote:
> 
>> Ok.  I've got an unusual problem.  My hard drive decided yesterday to
>>  turn read-only.  I can't write anything to it.  The data seems to be
>> all there and readable, but any write to the drive fails.  I have 
>> partitions of NTFS, FAT32, ext3, and reiserfs.  I'm able to mount all
>>  the other partitions and copy files off of them, but the reiserfs 
>> partition refuses to mount saying wrong fs type, bad superblock,
>> etc... Is there a reason that a reiserfs partition on a read-only
>> drive wouldn't mount?  I'd sure like to get what data I can off of
>> it.  Any ideas?
> 
> 
> Use UML (user-mode Linux) and arrange for writable backing store on 
> another fs.

To be more clear, the block device with reiserfs is the base for a COW
(copy on write) device which can be used under UML. For the writes, you
need to provide a file on a writable fs which will store the differences.
ReiserFS inside the UML will not notice the fact that you tricked it.

Carl-Daniel


-- 
http://www.hailfinger.org/

Re: read-only drive with reiserfs partiton not mountable

[Carl-Daniel Hailfinger]

Carl-Daniel Hailfinger wrote:
> [Sorry, I hit send a bit too early]
> Carl-Daniel Hailfinger wrote:
> 
>>Joel Ebel wrote:
>>
>>
>>>Ok.  I've got an unusual problem.  My hard drive decided yesterday to
>>> turn read-only.  I can't write anything to it.  The data seems to be
>>>all there and readable, but any write to the drive fails.  I have 
>>>partitions of NTFS, FAT32, ext3, and reiserfs.  I'm able to mount all
>>> the other partitions and copy files off of them, but the reiserfs 
>>>partition refuses to mount saying wrong fs type, bad superblock,
>>>etc... Is there a reason that a reiserfs partition on a read-only
>>>drive wouldn't mount?  I'd sure like to get what data I can off of
>>>it.  Any ideas?
>>
>>
>>Use UML (user-mode Linux) and arrange for writable backing store on 
>>another fs.
> 
> 
> To be more clear, the block device with reiserfs is the base for a COW
> (copy on write) device which can be used under UML. For the writes, you
> need to provide a file on a writable fs which will store the differences.
> ReiserFS inside the UML will not notice the fact that you tricked it.

If /dev/hdb8 is your read-only filesystem, try this:

./linux ubd1=reiser_cow,/dev/hdb8

and once you have booted the linux instance,

mount /dev/ubd1 /mnt

Another option is to copy the partition to a file on a writable fs and
loop mount it from there.

dd if=/dev/hdb8 of=/tmp/fsbackup
mount -o loop /tmp/fsbackup /mnt

The last option for coping with a readonly disk is to copy it over
completely with dd. Assuming /dev/hdb is your damaged disk and /dev/hdc is
your new shiny IDENTICAL model, you can also

dd if=/dev/hdb of=/dev/hdc

Note: If you are someone longing for SPEED, you can add bs=1M to the dd
commands. That should help quite a bit.


HTH,
Carl-Daniel
-- 
http://www.hailfinger.org/

Re: read-only drive with reiserfs partiton not mountable

[Zygo Blaxell]

On Thu, 03 Jul 2003 13:09:21 -0400, Joel Ebel wrote:
> Ok.  I've got an unusual problem.  My hard drive decided yesterday to
> turn read-only.  I can't write anything to it.  The data seems to be all
>   there and readable, but any write to the drive fails.  

Have you by any chance tried 'hdparm -r0 /dev/whatever'?  IDE disks have
a software read-only mode which may be turned on or off by hdparm or
similar commands.