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I have a user with an external hard drive that is no longer recognised: the drive letter does not appear in My Computer.

The drive is a Western Digital My Book Essential Edition (WD2500C032)

With help from the troubleshooting guide on the WD website, we have deduced that the most likely cause is a damaged or corrupt partition.

We have looked at the drive in Disk Management and the full volume appears as unallocated. We have also run SpinRite in recovery mode and that didn't turn up any defects, so the drive seems otherwise unharmed.

We would like to attempt to recover the data on the drive, and the WD site suggests "With a damaged partition, there is data recovery software that may restore the data. You can research the various kinds on the internet."

Not exactly the most helpful advice!

A quick search on Google yields a myriad of potential candidates, mostly commercial. The sheer number of offerings out there is bewildering. So can anyone offer any recommendations or experiences? Is it even worth trying? Have you ever successfully recovered a damaged partition on a drive, external or otherwise?

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You have pulled the drive out of the enclosure right? I know those things are welded in but you definitely need to cut it out and do any recovery with it plugged into a computer directly! It might not even be the drive. –  gyaresu May 12 '09 at 12:26

2 Answers 2

up vote 12 down vote accepted

Do not attempt any recovery of a HDD while it's still in an enclosure.

Cut that sucker out if you need to and plug it in directly via IDE or SATA.

Best software for partition recovery http://www.cgsecurity.org/wiki/TestDisk
Best software for file recovery http://www.cgsecurity.org/wiki/PhotoRec

I've succesfully used both several times a year with clients who get nuked drives.

On a drive that may have 'bad' or 'damaged' sectors it is highly recommended to do a Block level clone of the problem drive onto a new drive using GNU ddrescue. There are a couple of 'dd' based programmes. That one is the best.

Check the Cgsecurity article on Disk Duplication

Duplicating the disk and working on the new one will improve your chances of success due to possible mechanical failure of the problem drive during recovery.

Or if you just want to do it on the problem drive then run a Seatools test which is fine for any brand drive (they each have thier own progs but this is best):

All the programmes mentioned are available on livecd's. Below is a good list.

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never never try recovery to same drive unless you are sure what caused the problem and you are sure the problem wont happen again –  jake May 12 '09 at 12:39
    
@gyaresu - that's a beautifully comprehensive answer and just the sort of thing I was looking for. Many thanks. I am now intrigued as to why, exactly, one shouldn't attempt a recovery of an external HDD while it is still in its enclosure. –  Charles Roper May 12 '09 at 12:48
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@Charles Roper Hey Charles. You're welcome. It may well be that the problem is in the USB or Firewire controller circuitry. I know those drives are nasty to get apart (they do that intentionaly) but the next step up from software recovery is physically replacing the circuit board on the back of the drive itself. You can do that by buying an exact serial/batch model HDD. But that's another question :) –  gyaresu May 12 '09 at 12:58
    
TestDisk did the trick: it was indeed a partition gone AWOL. Your suggested apps are really great - solid, simple, utilitarian. Just how I like 'em. I couldn't make use of CloneZilla because, as far as I can gather, it requires a partition to operate on and it couldn't find one. Confession: I didn't remove the drive from its enclosure <queue sharp intake of breath>. While I would ordinarily take your advice, my instincts suggested that it wasn't a fault with the controller. It just didn't feel like circuitry gone wrong. Having said that, we are going to replace the drive ASAP. :-) –  Charles Roper May 12 '09 at 14:23
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You know @Charles Roper I think you're right. I messed up there with clonezilla. I gave you what I thought was a more simple tool when I should have given you what I actually use. I'll edit it for those who come upon this page :) Glad to hear you got it sorted bye the way! –  gyaresu May 13 '09 at 0:15

To answer the question title and since it's not tagged Windows I figured I'd throw in this for completeness:

If this was on a Mac, and the drive was formatted for HFS+ (standard for most Mac drives) or FAT32 I'd recommend the following steps:

  1. Open Disk Utility.app in /Applications/Utilties
  2. See if the partition is simply unmounted or if Disk First Aid will fix the issue - use Verify Disk first.
  3. Try DiskWarrior - it's a mainly one trick pony that any sys admin who works with Macs should know about because it works.
  4. If you need to do File Recovery try using FileSalvage or Data Rescue II
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Yeah, I toyed with the idea of tagging the question as Windows specific, but I figured the problem might not be OS-related, so erred on the side of keeping things open. Thanks for the answer - I'm sure it'll help people who have a similar problem on the Mac. –  Charles Roper May 12 '09 at 16:28

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