[Bug-ddrescue] Re: Using ddrescue for the opposite purpose?

[Antonio Diaz Diaz]

Michael Haardt wrote:
> I am looking for a program that:
> employs a log to store which sectors could not be erased and will not
> get confused about the file position upon write errors.  It should use
> the log to retry previously unerasable sectors without going again over
> already erased sectors.

Gnu ddrescue stores in the logfile info about the unreadable blocks, but 
nothing about the blocks already read. There is no efficient way to 
erase only the good blocks, except erasing them as they are read. This 
implies opening the input file r/w, and can lead to an unrecoverable 
disaster if the system crashes in the middle of a rescue.

Also, a sector may produce several read failures before being 
successfully read, and later be impossible to erase.

I think the changes you want are a bad idea for the stability of 
ddrescue, so I wont implement them. If you think otherwise, please, send 
me a patch.

Of course, a different program could use the logfile from ddrescue to 
erase the input file, but I don't know about the existence of such a 
program.


Regards,
Antonio Diaz.