merge two images using ddrescue

[raven4d]

Hi friends ,

i know this subject was reported several times , but unfortunatly , with no clear answer ..

i have a drive ( 500 GB ) that has unreadable areas ( between 190G and 195G ) that's fine .

using ddrescue with log , i imaged up to 190G then restarted ddrescue to start from 195G , but noticed that the speed of the imaging has dropped from ~26 MB/sec to ~10 MB/sec ,

so i started a new ddrescue imaging session that starts DIRECTLY from 195G , and imaging speed was ~26 MB/sec again .

now , as long as ddrescue fill unprocessed sectors and skipped areas with zeros , any ddrescue command to issue , to merge only non zero filled sectors ( according to their log files) ?

another question , that i dont really understand , why does the speed really dropped for the first session while it's fast like a charm for the second one on the same areas ?


thanks

[raven4d]

case solved , data recovered