Re: [Bug-ddrescue] ddrescue - resume backup with a little offset

[Marian Csontos]

On 08/30/2011 12:45 PM, Seagatevictum wrote:
> Hi!
> I ran into serious trouble. My Seagate drive with all my documents got
> corrupted. There’r about 10 bad blocks on the drive but each time the system
> tries to read from a broken sector the drive sets itself into busy mode and
> stops responding. Ddrescue is my best option because it can RESUME the image
> backup… but! For ex. I have a bad block at 3145 mg, and I want the backup to
> resume at 3155. I can do this using the log where the resume position is
> set. But how? I can’t really understand the 0x00000000 format either how
> does that correspond to the actual position? How can I add a “next sector”
> into the resume?
>
> Please help!

Hi, I think -i option is what you need:

> `-i pos'
>`--input-position=pos'
>    Starting position in input file, in bytes. Defaults to 0. In fill
>    mode it refers to the original input file. See the chapter Fill
>    Mode (see Fill Mode) for details.

3145 mg? Supposing that's 3145 MiB and you want to continue at 3155 MiB,
that's 3155 * 2**20 = 3308257280 (you can use python to calculate these)

  ddrescue -i 3308257280 INDEV OUTDEV_OR_FILE LOGFILE

Or in bash:

  ddrescue -i $((3155 * 2**20)) INDEV OUTDEV_OR_FILE LOGFILE

You will also want to use same LOGFILE to be able to resume if it locks 
again.

Also when it locks try the next megabyte, but on next pass try resuming 
3154 + 1/2 MiB, then + 1/4 MiB, and so on to get as much data as you can.

-- Martian