@Zuujin,
Zuujin wrote:
I thought it's a simple question
Actually you asked several questions, but some are based on wrong assumptions / understandings
so it would require a long correction of those misunderstandings, before even starting to try to explain each of your answers. Unfortunately that long teaching exceeds my time limit, especially since my answers would likely cause even more questions, so I didn't reply at all. That sometimes happens here - someone asks complex (or misunderstood) questions, and then is surprised when no-one replies.
For example:
Zuujin wrote:
[...] I took a closer look at the sense-register [...]
There is no "sense register" on a SATA drive. IMHO you need to learn more about (S)ATA registers, (e.g. perhaps starting with old versions of the ATA spec, which I think are an easier starting point, before moving on to the current version) and about the Linux libata architecture and what it is trying to achieve, to better understand what the Linux messages mean.
Some of the messages you are seeing are SCSI-type representation of ATA errors, so you need to learn about "SAT" - SCSI to ATA translation, as done by libata.
The short answer to some of your questions is that the retries you are seeing are
not commanded by the drive, but the drive will also be doing internal (invisible) retries (as normal). Therefore your questions asking whether retries are being done by the kernel
or the drive cannot be answered as a "simple question", because the answer includes "and", not "or".
Looking at other parts of the messages, I am concerned about the specific ddrescue command line being used, but that's a whole different discussion.
I use a different OS when I'm doing this (as part of my non-DR job), but IMHO your idea to remove OS retries is a good one, if you are limited to only using ddrescue etc. instead of using professional imaging equipment where the retries are already controlled. As
BlackST explained, there are limitations to the "amateur" approach.
I hope my short comments help to point you in the right direction for some topics you can research to better answer your own questions, but perhaps you will just be angry that I have not written the book that is needed to answer in more detail. If my comments help, then good. If not, then just ignore this and wait for someone else to reply
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