Re: [Bug-ddrescue] bug

[Antonio Diaz Diaz]

Hello,

sel janka wrote:
> when the usb stick unmounts itself(dont know why), the scanning
> process will still go on, but it will not warn the user nor will it
> write any more mapfile.

I understand that you are writing the mapfile to a USB stick.

This may be a bug in the kernel. Some OSs don't detect write errors 
properly (or at all) on some devices if direct disc access is not used. 
If the kernel does not return an error, ddrescue can't know that 
something went wrong.

If you are also writing the outfile to the same USB stick, you can try 
the option --odirect[1]. This should make the kernel return an error 
when the USB stick unmounts itself.

[1]http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Invoking-ddrescue

In any case, it is always a good idea to write the mapfile to a reliable 
location.


> you will have to start from the position where the log file was last
> written (like 16 hours ago...)P.S. - and maybe it should also start
> the fourth phase((Fourth phase; Retrying)) in reverse, so it might
> have better luck getting the data? (as it is already retrying).

Ddrescue will continue at the point where the mapfile was last written. 
If you want it to run in reverse you can use the --reverse option, but 
maybe 16 hours ago ddrescue was not yet retrying.


> and maybe even print some information on the screen about
> how much has been retried already? i think it only showed the error
> size while doing the retry phase (and i had to stop it because it
> hadnt written any log file - so now i dont know how much did it
> actually retry already...)

Thanks for the hint. Ddrescue 1.20 just shows the error size, but 
1.21-pre1 shows all sizes.


> and is the scanning any good if the Reallocated Sector Count and
> End-to-End Error SMART values are already very low? maybe even add
> some more information about when is it ok to run the ddrescue app and
> when it would damage the disk... (if it would?)thanks

Ddrescue should be run as soon as you detect or suspect that a drive is 
failing, in order to make a copy of you data[2]. Ddrescue should never 
damage a disk more than any other copying tool[3].

[2]http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Examples
[3]http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Algorithm


Best regards,
Antonio.