Rob Owens <robowens13@???> wrote:

> I don't know the answer to your read-only question. But having done some data recovery in the past, I've found that attaching the drive via USB and sitting the drive in the freezer during recovery can help in situations like this.

I have considered that, but for the moment, I'm getting "not too bad" results without.

> Also, besides ddrescue you can also take a look at photorec (part of the testdisk package).

ddrescue will do for me.
It's getting a lot of files complete - and those that aren't, I might well not bother with, or I'll accept holes in the recordings. There's a point of diminishing returns, and at the moment when I spot it throwing an error I'm just hitting ctrl-C and the script goes on to the next file* - I figure I might as well get those that recover "easily" first.

* I've also been fiddling with some of the options for quitting on errors and such.


Offlist I've been asked if I need the source mounted. In this case, yes - I'm doing recovery file-by-file. I usually just run ddrescue across the whole disk, but in this case I suspect it'll take a loooooooooong time, and given that it's a Seagate** which tend to have "interesting" failure modes which screw up ddrescue's methods, I don't think I'd get anything all that useful - and I'd have no ideas which files on the recovered copy were complete and which had holes filled with zeroes.

I'm now to the point of looking at the per-file logfiles, and moving the files that are complete without errors to another directory - leaving me with a better idea of how many are still to do. IMO that's the great thing about ddrescue - the way you can stop and restart it as often as you like, and it'll carry on where it left off (or where you've told it to go to if you fiddle with the log file).
Add in a bit of scripting and some options, and it's possible to get it to run through quickly, aborting files with errors, and then go back and have another run through those when you got the "easy" stuff.

** I don't intend ever buying another Seagate drive ever again. I;d had other makes go, but usually the electronics is fine - it's just the disk wearing out. Seagate have too many electronics or "crippleware" failures that make recovery hard or impossible. An "interesting" feature is that some drives just "stop working" once you hit an error - so ddrescue then whizzes through the rest of the disk marking everything past the first error as bad. That's just crap thinking on the part of whoever dreamt up the firmware spec.

For good measure, got an old PC from the loft to do this recovery with - and it packed in. Got another one that I blagged from work as surplus only a short time ago, and which was working fine - that doesn't work.