@guru: Many thanks for the image - yep, my ears look just like that

FYI, the issue I have seen with the 7200.11 drives with that SMART signature, causing drives to "disappear" from the OS, was not related to the DMA transfer hanging - that's why it didn't help when I forced PIO mode (i.e. disabled NCQ), in my investigation.
I understand that in general, you're completely correct about the possibility which you describe, and certainly you'll have much more DR experience than me.

I'm just saying that in my investigation, on those specific drives, with that specific SMART signature, an interface hang related to transfer mode was not the cause of the "drive disappearing" problem (which then requires a power-cycle to clear)

If your suggested change to PIO mode works for the OP, then great! But if that change does work, then it wasn't the same issue which I saw. This is the problem with remote diagnosis - the OP
seems to have the same issue as I investigated, based on what I have seen of the description and SMART data, but without him also having the same test equipment as I used, then I can't be completely sure... As we've both said, reverse cloning is something else that the OP can consider

Live long and prosper
