I am imaging a damaged 500gb ext3 filesystem using dd_rescue. By around 403gb of data copied, the program finds very numerous bad sectors (over 8000 so far) and runs miserably slow. If I stop the process and resume it reading backwards from the end of the disk (to know exactly where the troublesome area will start/end), will it destroy previously written data? I know it is not destructive if you resume in forward mode using the right ipos, but could not find any reference about its behavior when copying backwards.
Thanks in advance for your attention!
P.S.: I am aware that dd_rescue is also slow when reading backwards, but I want to salvage as much data as possible beforehand, or even more drastically, let the drive die in peace if all the last 95gb are damaged.