Recently I moved to Luxembourg. Before that big change took place, though, I had to sort out all my stuff to see what I will bring with me and what not. Of course my data would travel with me but since I had all kinds of things to do to prepare my departure I left the computing stuff for the last minute. I would take my trusty Macbook Pro with me and I would leave my old Windows PC behind. All my data though was in my PC that acted more as a media box. That machine had 3 HDs in it including the one I would take, a WD Green Caviar 1TB. I bought an external Enclosure for the disk but when I put the HD in the enclosure, I found out, to my horror, that neither the PC or the Macbook could read it. What went wrong? I put the HD on the PC again for sanity check and the data was there. I tried another HD with the enclosure to check that it was ok and it worked just fine. What was the problem? Unfortunately I did not have time to find out so I got the enclosure and the HD with me to figure it out when I had time.
That time was today. I tried using the HD with an another enclosure just to be sure but it acted the same. Mac OS X was managing to see that it was a drive but one that could not be read. Before you jump in, I have to say that the drive was, as I thought, NTFS and Mac OSX reads NTFS just fine in fact by installing NTFS-3G you can read AND write NTFS partitions in *NIX operating systems.
After checking with the Mac's Disk Utility I found out that the partition was not, in fact, NTFS but instead it was 'Windows LDM'. What the hell is Windows LDM? After some googling I found out that this is basically Dynamic NTFS partition. What had happened is that when I installed this HD on my old PC, Windows decided that it was a good idea to make this drive Dynamic since it already had two other HDs in the same machine. The problem is that by making it dynamic it can only be read as an internal HD from a Windows machine. Not even Windows machines could read it if connected externally, but only recognize it as a massive storage device that could no read. The anger!
Running TestDisk
Naturally, I had to find a way to change the structure of the partition back to basic NTFS without jeopardizing the data. Microsoft, on their support page, suggests that you should reinitialize the disk. Of course that means that you will loose all the data something I did not want to do under any circumstances. So, no Microsoft , thank you. After some googling I found some Windows utilities that can convert an HD from Dynamic to Basic on the fly. Since I had only the Macbook and the external enclosure, though , I had to make do somehow. I installed the demo versions of a few windows utilities such as Partition Magic using crossover but unfortunately none of them could "see" the external disk.
After more googling I found a fantastic Open source utility called TestDisk that could do exactly what I wanted, among many other things. Being Open Source it was native to Windows, Mac and Linux. I downloaded it and run it. It "saw" the external disk immediately and after following some simple steps it restructured the partition back to basic NTFS. Hoorah! You run the utility from the terminal select the drive, check the partition type(in my case it was "Intel PC") and when prompted, select to "write" the structure. That's it! Mystery solved, mission accomplished and I can again enjoy my data.