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So I'm about a week and a half into a ddrescue operation. The failing external hard drive is 2TB, with about 1.8TB of data, mostly photos. Here's what ddrescue is reporting at the moment, still in progress:

> sudo ddrescue -n -v -c 1Ki /dev/disk2s1 /Volumes/ExtraExternalHardDrive/recovered.img ddrescuelog.log

About to copy an unknown number of Bytes from /dev/disk2s1 to /Volumes/ExtraExternalHardDrive/recovered.img.
    Starting positions: infile = 0 B,  outfile = 0 B
    Copy block size: 1024 sectors       Initial skip size: 128 sectors
Sector size: 512 Bytes

Press Ctrl-C to interrupt
Initial status (read from mapfile)
  rescued:    1937 GB,     errsize:        0 B,  errors:       0

Current status
     ipos:    1998 GB, non-trimmed:  297795 kB,  current rate:    524 kB/s
     opos:    1998 GB, non-scraped:        0 B,  average rate:   8045 kB/s
non-tried:    9223 PB,     errsize:        0 B,      run time:  2h  3m 16s
  rescued:    1997 GB,      errors:        0,  remaining time:         n/a
percent rescued:   0.00%      time since last successful read:          0s
Copying non-tried blocks... Pass 1 (forwards)

Ok – so my question is: if I have 1.8TB of data on the failing drive, why do I now have 1.98TB of data in the recovery image file? And… how much longer is this thing going to go?

I've stopped the process multiple times during this effort, using the mapfile to restart each time.

Kamil Maciorowski
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Josh KG
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1 Answers1

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if I have 1.8TB of data on the failing drive, why do I now have 1.98TB of data in the recovery image file?

Because ddrescue knows nothing about filesystem and files. It reads and tries to recover the whole device. When it finally finishes, the recovered image size will exactly match the source device (disk or partition) size. I think the problem in your case is non-tried: 9223 PB. Maybe your failing disk reports the wrong size.

how much longer is this thing going to go?

Nobody knows. See my answer to another question.

Community
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Kamil Maciorowski
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  • So yes, my first pass just finished and the size of the recovered image is 2 TB. Thanks! – Josh KG Nov 20 '16 at 02:13
  • Ddrescue is known not to use very sophisticated methods to determine partition size. In my case it was simply failing with write/protocol error when going after the disk boundary. I eventually solved by converting the current_pos value inside the mapfile back to decimal, then using it as parameter for the --size= option. Even a slightly higher value was still borked otherwise (and seriously, it seems like the program is making fun of the user with these numbers that appear like a garbled mix of binary and SI prefixes) – mirh Jan 23 '20 at 15:26