How to recover partitions from an external hard disk?

Question

I have a 1TB Seagate external USB hard disk gone corrupt and is showing "You need to format the disk before you can use it" error in Windows 8.

What is the best way to recover the partition/data from this disk before I go on formatting it? Given that --

• Windows disk management shows this disk's filesystem as RAW.
• chkdsk utility doesn't work with RAW types.
• 'Recuva' didn't work either. "Unable to determine filesystem type" error.
• Quick scan using 'Partition Find and Mount' didn't work. I'm yet to try thorough scan.

Also, can Linux read RAW partitions without any tools? i.e. Will I be good to go if I just plug in this disk to a Linux machine?

Solution 1

Your drive's partition table is corrupted. Don't create new partition table or partitions or you may overwrite your data.

If you have a spare drive, you should make full backup of the faulty drive before proceeding. It can be done with dd tool (found in most Linux distributions, including LiveCD ones, eg. Ubuntu). You can do something like: (assuming /dev/sda is the drive you want to back up and /dev/sdb0/backup.img is the path for the backup)

dd if=/dev/sda of=/dev/sdb0/backup.img bs=4M

Now, the recovery part. The best tool for the job I can think of is testdisk which has already saved many disks that have suffered from the same issue, including mine. It will analyze your drive's structure and (hopefully) rebuild partition table, making your drive ready for further recovery.

Testdisk should fix your partitions, but before starting to browse them you should run chkdsk on each one. Boot to Windows and connect your drive. Press Win, type cmd, right-click the item that appears and choose Run as Administrator. Confirm UAC dialog, then run: (replace e: with your drive letter followed by a colon)

chkdsk /r e:

It can take some time, but when chkdsk is done you should have most of your data recovered.

Solution 2

The partition type could be Linux, which is not recognized by Windows. Conneting it to a Linux machine might reveal what the content is.

If you use Linux, you can use dd or dd_rescue to save the partition to an image.

On Windows you'd need a 3rd party tool like TrueImage or similar for backup.

If you want to see the disk content before, try FTK Imager Lite, which is free. It will display the contents as far as it can, so maybe you can at least detect if there's something on the drive or all zeros.

Comments

[user]

Windows says a partition is "raw" simply if it doesn't understand the structure of the data on it. Whether alternative software (like Linux) will be able to make sense of the partition depends on what's actually stored on it (after corruption). That Recuva can't figure out a file system type isn't a good sign, unfortunately.

[Karan]

I tried TestDisk as you said, it couldn't find any partition in that disk even after 'deeper' search. Any advice?

[Karan]

Surprisingly though, TestDisk's sister app PhotoRec seems to be working, dumping out common file-types from that disk altogether (without the directory structure) to a specified location. So, that's my last resort if I couldn't get TestDisk to work.

[gronostaj]

Yes, PhotoRec should be able to recover everything you haven't overwrited. It will just search for anything that looks like a file, ignoring partitions and filesystems.