Hello Dmitri,
Dmitri Kostin wrote:
Hello! Thanks for your program!
You are welcome. :-)
I have detected a bug. When using start or end positions that are not
rounded to hardbs (512 bytes) - I always receive an error of "bad
sector" with sizes varying from 0 to 512 bytes.
[...]
Oh! My HDD is such a slow one and contains many actual bads
that I use only -d -c1 -n -N.
This is not a bug, just a limitation. From the manual:
http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Direct-disc-access
"NOTE! Sector size must be correctly set with the '--sector-size' option
for this to work. Only whole sectors can be read; both
'--input-position' and '--size' must be a multiple of sector size."
You can try binary prefixes. For example -s49Ki instead of -s49k.
Also, my HDD being rescued contains areas with good
read rate (about 4Mb/s) sized about 600M, and between them - areas of
slow readable sectors (about 4 seconds per sector). I need some
options to immediately skip such slow areas to recover as much as
possible with minimal time spent. For example, such strategy as to
read forwards until slowing to min_read_rate or detecting an error,
then read backwards, until slowing or bad, too. Then divide the
maximum sized untried block by half and repeat.
Such "divide and conquer" strategies have already been tried in past
versions of ddrescue with bad results. They produce a lot of head
movement and no not reduce the total rescue time. Sorry.
Best regards,
Antonio.
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