Hello Nik, [email protected] wrote:
first of all - thanks for your great work with ddrescue. It has helped me a lot.
Glad to hear this.
There is one question which I had about the algorithm/strategy which ddrescue used. This question has been posted to the mailing list two years ago but has not been answered yet. You can find it here:
Yes. Sometimes I receive too many emails and forget to answer some of them.
Could you kindly do me the favor and answer this question? This would help me :)
Of course.
How does ddrescue work on defective sectors? When does it decide to skip sectors and much more important: how does it determine the size of sectors to skip or jump ahead?
You'll need to look at copy_non_tried() in rescuebook.cc to answer this. The important points are: 1) while copying the non-tried parts of the input file, ddrescue jumps forward every time it finds a bad sector. 2) the skipped size is increased until a good sector is found or the end of the current block is reached.
Also I have read something about backward reading capabilities but haven't seen ddrescue actually reading backwards. Does the current ddrescue read backwards? If so - when?
From http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Algorithm
"3) Read backwards one sector at a time the non-trimmed blocks, until a bad sector is found. For each non-trimmed block, mark the bad sector found as bad-sector and mark the rest of that block as non-split."
Best regards, Antonio. _______________________________________________ Bug-ddrescue mailing list [email protected] http://lists.gnu.org/mailman/listinfo/bug-ddrescue
