Thanks again to Dan and Yevgeniy for the info. I tried first doing
reverse read, but that just quit immediately:
$ sudo ddrescue -v -R -n --force /dev/sda /dev/sdb ddrlog.txt
GNU ddrescue 1.19
About to copy 2000 GBytes from /dev/sda to /dev/sdb.
Starting positions: infile = 0 B, outfile = 0 B
Copy block size: 128 sectors Initial skip size: 128 sectors
Sector size: 512 Bytes
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 951404 MB, errsize: 1048 GB, errors: 63
Current status
rescued: 951404 MB, errsize: 1048 GB, current rate: 0 B/s
ipos: 0 B, errors: 63, average rate: 0 B/s
opos: 0 B, run time: 0 s, successful read: 0 s ago
Finished
Note that it ran for 0 seconds. So I tried using -r1 to tell it to try to
recover more data. That ran for about 16 hours, but it said it didn't
recover anything. It did a lot of "scraping". I don't know if it
accompliched anything. Here's the output:
$ sudo ddrescue -v -r1 --force /dev/sda /dev/sdb ddrlog.txt
GNU ddrescue 1.19
About to copy 2000 GBytes from /dev/sda to /dev/sdb.
Starting positions: infile = 0 B, outfile = 0 B
Copy block size: 128 sectors Initial skip size: 128 sectors
Sector size: 512 Bytes
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 951404 MB, errsize: 1048 GB, errors: 63
Current status
rescued: 951404 MB, errsize: 1048 GB, current rate: 0 B/s
ipos: 2000 GB, errors: 63, average rate: 0 B/s
opos: 2000 GB, run time: 16.71 h, successful read: 16.71 h ago
Finished
On the bright side, I mounted /dev/sdb1 -- the main partition on the drive
I was writing to, and it looked really good. I mounted it read-only. I
can find files that I had lost and many of them look perfect. The home
movies that I thought were there seem not to be there. So I think I
copied them to an external drive, which is good news. I can see that some
files are corrupted -- like text files that are now just a mess of binary
characters -- but most files I've looked at seem perfect. So I'm pretty
happy with the results.
Thanks for everything!
Mike
On Wed, 16 Sep 2015, Dan Armbrust wrote:
> On 09/13/2015 04:02 PM, Mike Miller wrote:
>> At about 400 GB I picked up 4 errors, then nothing for a long time. I left
>> the house for a while and came back to this, which seems bad:
>>
>> $ sudo ddrescue -v -n --force /dev/sda /dev/sdb ddrlog.txt
>> GNU ddrescue 1.19
>> About to copy 2000 GBytes from /dev/sda to /dev/sdb.
>> Starting positions: infile = 0 B, outfile = 0 B
>> Copy block size: 128 sectors Initial skip size: 128 sectors
>> Sector size: 512 Bytes
>>
>> Press Ctrl-C to interrupt
>> rescued: 951404 MB, errsize: 1048 GB, current rate: 0 B/s
>> ipos: 2000 GB, errors: 63, average rate: 49658 kB/s
>> opos: 2000 GB, run time: 5.32 h, successful read: 4.53 m ago
>> Finished
>>
>> It's a 2 TB HDD, so it looks like it did half of it.
>>
>> Any opinions on the best next step?
>>
>> Mike
>>
> This is the point where I just end up using google myself... I use the rescue
> tools infrequently enough that I forget all of the tweaks and things to try
> with working around failing drives.
>
> You might have hit a default limit on the number of errors it will read
> before giving up... or, as Yevgeniy suggested, try running in reverse.
>
> On the plus side, at least your drive is still coming up to the OS. I've had
> a few, where, the only way I could get it to even appear as a drive was to
> put it in the freezer... then it would work for about 20 minutes, till it
> warmed up, then fail again...
>
> You just keep trying to get as many blocks read as possible, and then at some
> point, you call it good - and move on to trying to do the ext4 recovery steps
> on the restored drive, to try to restore the file system to a state where it
> will mount.
>
> Good luck,
>
> Dan
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