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Data recovery and disk repair questions and discussions related to old-fashioned SATA, SAS, SCSI, IDE, MFM hard drives - any type of storage device that has moving parts
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ddrescue and offsetting

December 15th, 2016, 8:34

Hi,

I'm trying to use ddrescue to recover the data from a formatted (unknown partition from data recovery company) disk (disk1) onto disk 2, which has been formatted as HFS+. I have seen that an offset can be used on disk1 to begin the cloning process after the boot sector, but can the cloned data be placed after a different offset on disk 2 or if it is the same offset position, would it just be a case of then attaching the disk2 to a macOS system and then being able to view all the cloned data, at least that which was recoverable?

The flag I have found is an -o flag.

-o, --output-position=<pos>
starting position in output file [ipos]


Which came from this site http://forensicswiki.org/wiki/Ddrescue#Gentoo.

I have posted the same question on an Ubuntu forum as I'm using Ubuntu to perform the recovery, the site for the first post is https://ubuntuforums.org/showthread.php?t=2346436.

If I have broken any forum rules about cross-posting or something like that, then please accept my apologies.

Many thanks for any responses.

Re: ddrescue and offsetting

December 15th, 2016, 18:44

Using the --output-position option will definitely move the data to a different location on the destination than it was on the source. This is very bad for data recovery, as filesystems are based on location. You should make an exact clone and run some data recovery tools on the clone to see if data can be found/recovered.
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