On 3/7/2014 8:22 AM, michalpl7 wrote:
ddrescue -f -g -n /dev/sdb /dev/sda /mnt/rescue1.log
My first thought is wondering what you meant by the "-g", as that is
not a valid option. Depending on what you meant, it could affect the
accuracy of this reply.
1) Does ddrescue overwrite data on /dev/sda (target) if it can't get it ( bad sectors ) from /dev/sdb or data from 1st run will remain on target drive?
No, ddrescue does not write data to the target if the read fails. So
if sector 100 had a read error on the source drive on the second
run, sector 100 on the target drive would still have whatever data
was there before the second run. So any data that was good after the
first run would still be good on the target.
2) Does ddrescue overwrite data on /dev/sda (target) if I didn't specify log file from 1st run ( create new one )?
Yes, ddresuce will overwrite the data. But as long as it was the
same source and target, and since only good data is written, you
will not loose any good data that was written to the target on the
first run, and could possibly gain good data from the second run.
3) If answers to questions above are YES then I understand that it copy this new run in same place ( sectors ) as 1st one so I can put it together in data recovery application?
Maybe someone else can answer this better than me, but I don't see a
problem with continuing your rescue using the first log, since it
was finished as commanded. I am assuming you wish to continue
without the -n option to further the rescue. Did you also do a full
run with the second logfile?
If you really want to be technical and make sure you have the best
of both runs, there is a function in ddrescuelog where you can merge
2 logfiles, but I am not familiar enough to give any advice on that.
See the description below from the ddrescue manual.
- '--or-logfile=file'
- Perform a logical OR operation between the finished blocks
in file
and those in logfile, and write the resulting
logfile to standard
output. In other words, in the resulting logfile a block is
shown as
finished if it was finished in either of the two input
logfiles.
Scott
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