Most of the time I can just run ddrescue and it copies the disk or partition which I then can work on. Just occasionally, I have to get into the nitty-gritty and try to recover bits of the disk. At that point, I have to go and read the manual to refresh my memory.

One of the things I struggle with is the terms trimmed and scraped. These are described in section 4 about the algorithm. However, they are described amongst lots of other information so it is hard to get the concept of what they actually mean. Even worse, there are forward references, eg, trimmed and scraped are referred to in the section on copying. So understanding requires reading the algorithm part 17 times :-)

So could I suggest that these terms be included in section 2 of the manual, Basic Concepts. I know this is difficult as they are so dependent on understanding what has gone before. I have tried to define the terms for my own use in a general way. Are they correct?

Copying: Copies blocks, skipping those that return an error or are slow. May skip way beyond the problem block to escape extended faults???

Trimming: For each skipped block, reads from the beginning and end by sector to narrow down the range of faulty sectors. This can leave a number of good sectors between the first and last bad sector.

Scraping: Reads all the unread parts of the disk to attempt to recover any good sectors not detected by trimming.

Retrying: Reads every bad sector multiple times in case it is possible to recover some information from it.


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