Re: [Bug-ddrescue] How to properly repair rescued image?

[James Bardin]

James W. Watts wrote:
> Hi Ariel,
>
> Thanks again for the info. The reason I didn't CC the bug list initially was 
> that I didn't want to
> misuse the list as a support forum. If it truly is a bug submission vehicle, 
> then I apologize to
> the friendly folk who are on the list. But if support is fair game, then I 
> welcome all responders.
>
> Thanks for confirming my fears. I knew I was gambling with fate. Thank goodness 
> my drive made it
> thru ok with HDD Regenerator. You mentioned that you would have let ddrescue 
> work on the drive
> directly. How would you do this? How would you know which infile to point 
> ddrescue to? You
> suggested to let ddrescue work on the first sector only. But how?
>   
You can ddrescue an entire disk, and attempt to fix the partitions from 
the image.
Then you can mount the partitions using an offset option. Forensic tools 
(like Sleuthkit) may be able to do more.
$ fdisk -l -u image_file

Disk /dev/sda: 160.0 GB, 160000000000 bytes
255 heads, 63 sectors/track, 19452 cylinders, total 312500000 sectors
Units = sectors of 1 * 512 = 512 bytes

  Device Boot      Start         End      Blocks   Id  System
/dev/sda1              63    61866314    30933126   83  Linux
/dev/sda2        61866315    64019024     1076355   82  Linux swap / Solaris
/dev/sda3        64019025   312496379   124238677+   5  Extended
/dev/sda5        64019151   239818319    87899584+  83  Linux
/dev/sda6       239818383   312496379    36338998+  83  Linux


To mount sda5 from this image (assuming a 512byte block size), mount it 
with an offset of the start_address*512 (64019151*512=32777740800)

mount -t ext3 -o loop,offset=32777740800 image_file /mnt


> How do you point ddrescue to a source drive that is not listed in /dev?
>
>   
If the base device is listed, but not the partitions, I would rescue the 
entire disk. (maybe ddrescue will copy the partition table at that 
point). If there still isn't a partition table, try some tools like 
TestDisk to rebuild it on the image (or better, a copy of the image ;).

> What's the best way to deal with what I have now -- a ddrescue'd image of my 
> crashed XP NTFS
> partition?
>
>   
If you can move the partition image to an ntfs drive that can hold it, I 
would run GetDataBack on the image file, and not worry about writing it 
to a disk.

-jim