Re: [Bug-ddrescue] About converting partition log to disk log

[Scott Dwyer]

On 11/5/2016 1:42 PM, Joe Kickman wrote:
> Thanks, Scott Dwyer!!! Superb!
> The first part I've done myself, I first created the whole disk image, then 
> copied the partition image to the disk image, specified at first to copy only 1 
> sector at the partition start to check whether the parameter -o was set 
> correctly. It really was! [ -s1s -o206848s ]. Then I omitted -s - and specified 
> the partition_copy_log as a domain file - to copy only the rescued parts of the 
> image [ -m ~/usbdrive/clone1.log ].
> The second part I did manually. Luckily - there were only about 80 lines to 
> correct. I added +06500000 to each block_start_position, then added a line 
> before all existent positions: 00000000  06500000 ?
> Then ddrescueview showed me the maps - partition and disk - by their logfiles - 
> and I became sure I did it right!
> Then I copied only the MBR, then filled it with zeros on the initial disk 
> (using free version of DMDE disk editor) - and then ddrescue was run on the 
> whole disk. It works fine. I am using -R -c1 to be sure to copy without freezes.
Glad you have it figured out.
>   Also sometimes it occured useful to disable drive cache with hdparm [ sudo 
> hdparm -A 0 /dev/sdb ] and [ sudo hdparm -a 0 /dev/sdb ]. It helps to read 
> carefully when being near the problematic areas.
> Does the direct mode work in the same way?
Direct mode disables the caching in the OS, not on the drive itself, so 
it is not the same. However, in Linux using the --direct option in 
ddrescue usually provides better results (not as long to process errors, 
seems to bypass some OS retries).
> Also, I propose to add an option to ddrescue to make decimal output - to be 
> easier to process the logfile-mapfile with spreadsheets.
> By the way, Scott, which one did you use? I considered using spreadsheet 
> programs - but do not know any capable of understanding hex numbers :(.
I used Excel in Windows because I have it, there is the function 
HEX2DEC, but it requires an extra step of removing the leading "0x" (a 
Google search provided quick results). I just checked Gnumeric 
Spreadsheet (for Linux) and the hex2dec function works with the leading 
"0x" still attached :)
There is a function to switch back from decimal to hex, but then you 
have to add the "0x" back in front if you wanted to import it to a 
ddrescue log file so it knows the numbers are hex. Still all can be done 
in the spreadsheet, it just takes more work using more columns and formulas.

Regards,
Scott