Re: [Bug-ddrescue] ddrescue very slow, and specific data to copy help.

[Antonio Diaz Diaz]

Hello Andreas.

Andreas Boman wrote:
> The first pass ran with options -g -n (no -f version 1.11) ran very 
> quickly (around 100 MB/s), seemed to recover around 600 GB or so before 
> completing.

You did a first pass from drive to drive with the option -g 
(--generate-logfile)? If you did, you'll need to begin the rescue again 
with an empty logfile. All your copy is garbage.

--generate-logfile is so dangerous when not used correctly that it has 
its owh chapter in the manual:

"However, if the destination of the copy was a drive or a partition,
(or an existing regular file and truncation was not requested), most
probably you will need to restart ddrescue from the very beginning.
(This time with a logfile, of course). The reason is that old data may
be present in the drive that have not been overwritten yet, and may be
thus non-tried but non-zero."


> Currently I can live with this amount of data loss, however it looks 
> like the md superblock has not been copied over to the new disk, 
> although it is fine and readable on the old one, and I need that to 
> restore the array with the new disk.

If the destination drive had non-zero data in the place where the 
superblock resides, ddrescue won't copy it (it thinks the superblock is 
already copied).


Regards,
Antonio.