External HD partitions disappeared after installing it directly to computer via SATA

unixunderground · 11-02-2013, 05:47 AM

I had an external 4TB drive (WD MyBook) that had been working without issues for several months, that I now decided to mount on the same computer, but only via SATA , as to get faster transfer speeds than via USB 2.0 .

So anyways, I removed it from its enclosure, connected it via SATA, booted the computer but then when I tried mounting it, issues started arising.

First of all, I launched gparted, which showed the disk as "unallocated" and printed a "Error: Unable to open /dev/sda - unrecognised disk label."

So then I googled a bit, and followed this guide I found online.

That solved the "unrecognized disk label" issue right away, but however upon opening gparted again, the entire disk is still being showed as "unallocated"

How could this happen? Is there any way to fix this or should I consider all my files and partitions permanently deleted? What did I do wrong?

BTW, I am running Debian 7 Wheezy with everything updated to the latest releases.

Thanks in advance to anyone who will take time to help me out

EDIT:
Here's an fdisk -l , which as you can see seems to be indicating that the disk is empty, even though it most definitely isn't.

Quote:

Disk /dev/sda: 4000.8 GB, 4000787030016 bytes
255 heads, 63 sectors/track, 486401 cylinders, total 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000cc802

Device Boot Start End Blocks Id System

Disk /dev/sdb: 80.0 GB, 80032038912 bytes
255 heads, 63 sectors/track, 9730 cylinders, total 156312576 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b8fe1

Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 149886975 74942464 83 Linux
/dev/sdb2 149889022 156311551 3211265 5 Extended
/dev/sdb5 149889024 156311551 3211264 82 Linux swap / Solaris

unSpawn · 11-02-2013, 12:47 PM

Check if the drive uses some form of encryption?

syg00 · 11-02-2013, 04:50 PM

Quote:

Originally Posted by unixunderground

What did I do wrong?

- not properly investigating the issue
- not understanding the ramifications of following that internet advice
- not taking a backup
...

What is most important is the messages (see dmesg) at time of error. If there were any.
As the parted doco says mklabel writes a new partition table - by definition empty. The fdisk listing is looking at the partition table, not what's actually on the disk, so your data is probably "safe".
Given the size of the disk, I'd be guessing gpt as the proper (initial) partition structure (label type) - but that shouldn't of itself cause a problem. I'm surpised parted (and gparted) couldn't handle gpt, so the problem is likely something else.
"testdisk" is the normal answer to partition screw-ups, and appears to support gpt. It may be able to rebuild a gpt partition structure to get at your data - most people report good things about it.