Monday, September 10, 2012

Yet more data recovery

Got a hard drive that has confounded ZeroAssumptions. Doh! It has obvious bad sectors.  Time to Clone.

Found another that is the same size and grabbed a copy of HDD Raw Copy Tool from Here.

Cloning the drive to the good one.  Just waiting for that to finish, then I can run ZA on the clone.  Fingers crossed I get it mostly back.


HDD Raw Copy Tool seems to work... up to a point. It has crashed twice (requiring a complete restart) and gracefully exited once (at 30% complete) claiming that the device was removed.

The interesting thing is that even with a partial image recovered... the destination disk will mount and seems to have a readable partition table and file allocation table.  Shame it will not get all the way through.  Anyway, after wasting 4 days on it... its time to move on.

The interesting thing from HDD Raw Copy was that it consistently hit the same 5 patches of errors.  After which it seems to happily copy at a good pace without missing a beat... until it stopped working.  Would love to be able to re-start the copy at arbitrary offsets.  Which leads me to...

I have been looking at ddrescue and decided it was the next option. It has the ability to stop and restart and lots of other interesting options. Fairly cryptic UI... but thats fairly normal for cmd line tools in linux land.  I also have issue with how vague some of the help files are... but then I'm not really spoilt for choice at this stage.

First attempt, boot a Ubuntu live cd and install gddrescue... failed miserably with various errors. Mostly to do with not being able to find the repository.  Still a bit new at that so I figure its more to do with it being a live CD than a full install.

Second attempt, got a copy of Ubuntu-rescue-remix which already has ddrescue installed.  Boot... to a bit of a weird terminal screen as the shell.  Fair enough. (Not exactly luxury but functional enough)

Introduced the USB drives (the damaged one and the one I want to copy to) one at a time so I could figure out what the device names were.

/dev/sdb1 is my source device
/dev/sdc1 is my destination device

I have to bugger around with mounting and unmounting them until ddrescue seemed happy to proceed. This was a bit of trial and error as the error messages were as usual completely cryptic.

My final setup was to allow the destination device to automount, which sorted it out as read/write with all the usual mounting options.  While the source device automounted when I plugged it in, but I then unmounted which made ddrescue happy.

sudo umount /dev/sdb1

Then its just a case of figuring out how to run ddrescue.

The command I ended up using was straight from the manual example.

sudo ddrescue -f -n /dev/sdb1 /dev/sdc1 logfile

In hindsight (after reading a bit more) it may have been interesting to add the -v flag (for verbose) but I can live with it as it is.  It would also have been better to give the logfile a more meaningful name.

Anyway, its rolling and seems happy at the moment.  Has already foun one error...


So after about five days copying... (there was a weekend in there, so my estimate is about ~4 days) the clone has finished successfully. Only about 8MB and change that it could not copy.  Not bad for about 8 reported errors. 

Anyway,  now back to Windows and ZeroAssumptions. 

ZA is totally ripping through this scan.  Its done the first two passes in about two hours and is well into the third already.  (For comparison, to get to this stage on the old disk took about 3 days... which was shorter once I tuned the timeout period and the bad sector skip factors... got it down to two days or so)

Feeling quietly confident...

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