[linux-lvm] A way to bypass LVM and extract the raw data off?

[IpSo]

Quoting Andreas Dilger <adilger at turbolabs.com>:

> On Jan 08, 2002  19:02 -0800, IpSo wrote:
> > Yup! I'm confident everything as far as the reiser filesystem is fine,
> > just LVM is very confused. 
> > 
> >    Device Boot    Start       End    Blocks   Id  System
> > /dev/hda1   *         1       507    255496+  82  Linux swap
> > /dev/hda2           508     39813  19810224    5  Extended
> > /dev/hda5           508      4633   2079472+  83  Linux
> > /dev/hda6          4634     39813  17730688+  8e  Linux LVM
> > 
> >  
> > >     If you have the HD space, you could try dd if=/dev/hda6
> of=/some/file
> > > 
> > >     Then mount -o loop /some/file /mnt/point -t reiserfs. 
> > > 
> > >     I don't think this would do any more damage. 
> >
> > I'll give it a shot I guess, won't this loopback file contain the extra
> LVM
> > information and cause problems when trying to mount it though? Does the
> LVM
> > information take up the first 2mb or something that I could set the offset
> as,
> > so it doesn't carry over to the loopback file?
> 
> No, it uses a variable amount of space.
> 
> What you could do is try
> 
> od -Ad -a /dev/hda6 | grep "R   e   I   s   E   r   2   F   s"
> 
> and start your dd 65584 bytes before the address at the line this is
> found on (it should align to an even block boundary).

At the "line", I tried the command and I got about 1000+ lines that seem to
match. I assume I just try from the first line minus 65584 (3276800) like you 
said? 

[root at ipso big]# od -Ad -a /dev/hda6 | grep "R   e   I   s   E   r   2   F   s"
3342384  bs nul soh nul   R   e   I   s   E   r   2   F   s nul nul nul
3383344 eot nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3424304 eot nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3498032 stx nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3547184 eot nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3616816 ack nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3706928  nl nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3825712  nl nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3842096 dc4 nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
3932208 dc4 nul soh nul   R   e   I   s   E   r   2   F   s nul nul nul
3944496 dc4 nul soh nul   R   e   I   s   E   r   2   F   s nul nul nul
3956784 dc4 nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
4001840 dc4 nul stx nul   R   e   I   s   E   r   2   F   s nul nul nul
...



dd if=/dev/hda6 bs=512 skip=3276800 of=/big/backup_hda6.bin

-rw-r--r--    1 root     root     16478502912 Jan  9 12:50 backup_hda6.bin

Still won't mount the file. :( Even after a --rebuild-sb.

I also tried: (/dev/hda)

dd if=/dev/hda bs=512 skip=3276800 of=/big/backup_hda6.bin

-rw-r--r--    1 root     root     18870119424 Jan  9 13:41 backup_hda6.bin

Still no go. 

> 
> Cheers, Andreas
> --
> Andreas Dilger
> http://sourceforge.net/projects/ext2resize/
> http://www-mddsp.enel.ucalgary.ca/People/adilger/
> 


IpSo

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