ddrescue and partition table

[Trio3b]

mandriva linux. 40gb hdb  (hdb1 34gb, hdb3 3gb) used for backup went bad. error message "no permissions"., or wrong fs, bad superblock etc.

Moved to new PC with hda. partitioned

hda1 - /
hda6 - /home
hda7 - /resue  42gb specifically to hold hdb1

tried ddrescue -n /dev/hdb1 /dev/hda7 logfile

now hda7 won't mount with same error message  of "no permission" or wrong fs, bad superblock

permissions are given

I believe partition table of hdb is corrupt. Is ddrescue copying bad partition table from hdb to hda7 so it won't mount?

Any help appreciated

[Ken A Scott]

Have you tried running testdisk on this troublesome partition to see
what you might learn (and/or correct)?
http://linuxappfinder.com/package/testdisk
It is found on a number of Linux rescue liveCds.
Cheers
Ken

On Tue, 03 Nov 2009 22:06 -0800, "Trio3b" <ocki@...> wrote:

>
> mandriva linux. 40gb hdb  (hdb1 34gb, hdb3 3gb) used for backup went bad.
> error message "no permissions"., or wrong fs, bad superblock etc.
>
> Moved to new PC with hda. partitioned
>
> hda1 - /
> hda6 - /home
> hda7 - /resue  42gb specifically to hold hdb1
>
> tried ddrescue -n /dev/hdb1 /dev/hda7 logfile
>
> now hda7 won't mount with same error message  of "no permission" or wrong
> fs, bad superblock
>
> permissions are given
>
> I believe partition table of hdb is corrupt. Is ddrescue copying bad
> partition table from hdb to hda7 so it won't mount?
>
> Any help appreciated
> --
> View this message in context:
> http://old.nabble.com/ddrescue-and-partition-table-tp26191466p26191466.html
> Sent from the Gnu - ddrescue mailing list archive at Nabble.com.
>
>
>
> _______________________________________________
> Bug-ddrescue mailing list
> Bug-ddrescue@...
> http://lists.gnu.org/mailman/listinfo/bug-ddrescue

--
  Ken A Scott
  kscott9@...



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[andrew zajac-2]

Well, you've made a backup of the partition so the partition table on sda is irrelevant.  Did the partition table on sbd point sdb1 to the wrong spot?  Unlikely.

Your superblock may be messed up.  Linux Ext filesystems keep backups of the superblock.  Just try to mount the filesystem with one of the backups:

sudo dumpe2fs /dev/sda7|grep superblock

This will list the superblocks.  You need to multiply the block size by four to translate from disk blocks (512 bytes) to filesystem blocks (4096 by default).  Something along the line also uses 1024 sized blocks so that's why 4 is appropriate.  for example:

Backup superblock at 32768, Group descriptors at 32769-32771

32768 * 4 = 131072, so,

andy@andy-desktop:~$ mkdir mnt

andy@andy-desktop:~$ sudo mount -r -o sb=131072 /dev/sda1 mnt

andy@andy-desktop:~$ ls mnt
bin    etc         initrd.img.old  mnt   sbin   tmp      vmlinuz.old
boot   home        lib             opt   srv    usr
cdrom  initrd      lost+found      proc  store  var
dev    initrd.img  media           root  sys    vmlinuz


Use sda7 in your case... I hope this helps.

Andrew Zajac



--- On Wed, 11/4/09, Trio3b <ocki@...> wrote:

From: Trio3b <ocki@...>
Subject: [Bug-ddrescue] ddrescue and partition table
To: Bug-ddrescue@...
Received: Wednesday, November 4, 2009, 1:06 AM

mandriva linux. 40gb hdb  (hdb1 34gb, hdb3 3gb) used for backup went bad.
error message "no permissions"., or wrong fs, bad superblock etc.

Moved to new PC with hda. partitioned

hda1 - /
hda6 - /home
hda7 - /resue  42gb specifically to hold hdb1

tried ddrescue -n /dev/hdb1 /dev/hda7 logfile

now hda7 won't mount with same error message  of "no permission" or wrong
fs, bad superblock

permissions are given

I believe partition table of hdb is corrupt. Is ddrescue copying bad
partition table from hdb to hda7 so it won't mount?

Any help appreciated
--
View this message in context: http://old.nabble.com/ddrescue-and-partition-table-tp26191466p26191466.html
Sent from the Gnu - ddrescue mailing list archive at Nabble.com.



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