ddrescue slows down to a crawl

[Aquous]

Hello,

Yesterday morning, I very unexpectedly lost my external 1 TB USB drive . The initial symptom was Windows refusing to open a certain directory, with the drive needle audibly skipping back and retrying to read the problematic sector, while the GUI was totally frozen. After four such audible retries, I thought 'oh crap' and unplugged the drive. When I plugged it back in, Windows couldn't read the disk at all anymore. Linux, however, can read from the (undamaged) areas of the disk just fine; if I do a 'dd if=/dev/sdg bs=512 count=1', I happily see what looks like a regular MBR.

None of the data on it is critical, but obviously I'd still like to salvage as much as I can. So, I bought a new drive, and started to ddrescue the bad drive to the new one. This is the command I'm using:

[Ant P.]

It may be useful to run `smartctl -a /dev/sdg` every so often while that's running. It won't make it go any faster, but it might at least explain why it's slow.

Hopefully it's just struggling to read a (small) bad part of the disk, and not something permanently dead.

[i92guboj]

ddrescue is doing all it can already, so, sitting around is all you can do. It is perfectly normal that it is taking so long, and whether you'll get the relevant pieces of data back is unpredictable. How long it will take depends only in how much of the disk is broken. It might be a small part, or most of it.

ddrescue will attempt its best, and continue if the data can't be recovered after some tries. In fact, you won't even know if your data is being recovered at all until it finishes.

That's the best you can get without getting to the physical level, that is, disassembling the driver and using specialized hardware to get the data, or whatever they do in data recovery laboratories.

[frostschutz]

You can manually send it to another region. And then retry the problematic one later. The examples in the manpage should show this.

The "best" option should be to get as much data off it as quickly as possible, I don't know of any software that meets this criteria out of the box. Slowing down to a crawl and thus spending hours not reading perfectly readable regions further behind is far from the "best" you could do.

Also you might try your luck with the --min-read-rate= option...

[Aquous]

Thank you very much for your replies!

smartctl doesn't show anything interesting; it shows 8 errors which have all popped up at the same moment, indicating that I probably damaged the drive during transport (I move it around rather frequently; must be more careful with that, it seems ). I can't see any hint of specific regions being (or becoming) damaged during the ddrescue.

frostschutz, thank you for suggesting I use --min-read-rate! That helps a lot - can't believe I missed that reading the man page

[frostschutz]