Re: [Bug-ddrescue] an issue with reading cd-rom discs on linux

[Antonio Diaz Diaz]

Cezary Sliwa wrote:
> What is the purpose of such checks? One may have a partial (short)
> copy of the file to rescue he wants to merge in. Done blocks are OK in
> such a case. Just take care not to truncate the rescued file or the
> log.

Ddrescue does not work like this. It is designed to copy a file/device 
whose size remains constant. It even provides an option 
(--verify-input-size) to verify that the size of the input file and the 
size recorded in the logfile match.

As Felix says, one of the purposes of this check is to avoid ruining the 
rescue if you give the wrong input file.

OTOH, if you have a partial copy you want to merge, you need the 
corresponding partial logfile, or the merge would become an overwrite.

(Ddrescue does not write zeros to the output when it finds bad sectors 
in the input, but it does write zeros to the output when it finds zeros 
in the input).


Regards,
Antonio.