[edit: problem solved, see here]
I’m in the verge of loosing some important data which I would like to avoid by any means.
So this is my last hope. Can you, dear internet souls, advice me into some reasonable solution?
Basically I installed windows 8 through Bootcamp with a 100GB partition.
I then decided 50GB would be enough, and from inside windows I shrinked the partition from 100GB to 50GB.
That left me with a 50GB unallocated partition. So I clicked in the partition (again, from windows8 disk utility) and ask to format it to exFAT.
Now the problem: windows asked me to assign a letter to it, and  I picked the first one avaiable. As it turned out this was taken (by the Mac I suppose) and windows did something strange. From that point on I could no longer see my OSX partition in the boot window (the one I see when keeping alt/option pressed). I couldn’t even boot on windows (it jumps to some Windows auto-repair attempts loop which now I regret may have only made my situation worse).

Oh God … Blue Screen of Death revamped?

Now the troubleshooting part:

If I boot up with a MountainLion USB boot stick (thanks PB!) I can go to the Mac Disk Utility and see three partitions in the HD (400GB, 50GB, 50GB). The first one (400GB) was supposed to be my OSX partition, but it says:

Mount Point : Not mounted
Partition Type: Windows_LDM
Capacity : 400.86GB
Available :
Used :
Now if I boot up with Linux (Ubuntu Rescue Mix live dvd) and try any of the basic recovery commands I get:
Error:  Both the primary and the backup GPT tables are corrupt. Try making a fresh table, and using Parted’s rescue feature to recover partitions.
Any hardcore suggestion? I’m accepting anything from linux hacks to redo the GPT table forcing it to match my original ideal tables, or mac or, …
I don’t care about the windows partitions, so for me they are as good as dead. I’m only concerned about the OSX data.
I remember from my days of Linux that I could try to force a change of partition type without reformatting. But that will only work if windows changed the partition type but didn’t did it properly. I’m not sure this is relevant though. I’m not even sure whateheck a GPT table is …
AppleCare is not much more helpful (they are nice to speak with, but didn’t get very far). So the internet is my last hope …
Thanks a lot, any help is appreciated 🙂

11 Thoughts on “I need some serious OSX help

  1. Todd McIntosh on November 24, 2012 at 4:04 am said:

    I know you’re looking for more low level advice, but you might want to give DiskWarrior a try.


  2. Ugh! That sounds ugly.
    I recovered some broken partitions with testdisk in gnu/linux, but I’m not sure if it support this type of partition.
    After a quick search I bumped with this:

    It’s adviseable to clone the disk if you have a spare one before trying this kind of things, but even if you don’t it looks like something that’s worth to try.

    Good luck with that, and next time DON’T rely on windows to partition your harddrive.
    Actually, I think the advise should be: DON’T rely on windows. Period.

  3. mfoxdogg on November 24, 2012 at 8:28 pm said:

    I would recommend getting a copy of the partdMagic live cd, and it runs entirely in ram thus having full access to disk, and do what it says, use GPartd and use the rescue option

  4. Kenan Bölükbaşı on November 24, 2012 at 10:28 pm said:

    CAUTION: All information below are coming from someone who doesn’t really know what he is saying and doesn’t have a Mac. I just wrote down anything I can think of in case it might somehow help.

    I am not knowledgeble in the subject but I did some reading on it after reading your issue. So again, don’t rely on my recommendations, but it seems your MBR (that needs to only point to a GPT partition and let GPT take care of the rest) is modified by Win while shrinking+partitioning, probably causing the exclusion of GPT from MBR. If the partition management is done via GPT MBR normally doesn’t do anything except pointing to GPT (unless you modify it to be a Hybrid MBR) it seems. GPT includes the partition information to boot OSX. So when GPT partition is omitted from MBR by partitioning operation done by Win, now you can’t boot OSX. And Windows probably didn’t modify the GPT to represent the newly modified table structure, so when you try to read GPT using a recovery tool, you get corrupt GPT error, because the partition structure it shows does not fit the actual structure in disk now.

    It might as well be the case that MBR is still pointing to GPT but doesn’t let you use it while booting since it is corrupted.

    To fix the situation I believe you might try running “gdisk” utility in a live linux terminal and try to fix the GPT in order to represent the actual partition structure of disk first, then fix the MBR so it can see GPT again. Fixing MBR might be rather trivial, I would concentrate on fixing the GPT according to current disk partitions first.

    One page I found on repairing GPT is this:

    I suggest gathering precise information on what is recorded in your MBR, what is recorded in your current GPT, and what is the actual partition structure etc. then adding those information to your post.

  5. Kenan Bölükbaşı on November 25, 2012 at 1:53 am said:

    Here is an idea, your HFS partition (of OSX) might be encapsulated in that LDM volume, since LDM is kind of like a container, so if you can boot to windows using a Windows that run from usb, system will probably see the LDM volume. But HFS filesystem of OSX is not supported in Windows, so you need something like this to access the HFS partition if it is actually in LDM: http://www.catacombae.org/hfsx.html (it says run as admin to let it detect disk volumes)
    you can also search for windows hfs drivers in case program in above link doesn’t work.

    also it might be possible to mount the ldm partition in linux via something like this:

  6. Hello everyone, thanks for the help. I just finished a `dd if=/dev/sda /media/usb7/sda_backup` (it took 30 hours to dump all the 500GBs). I will now try gdisk in case the data is still around.

  7. Testdisk ( http://www.cgsecurity.org/wiki/TestDisk ) can help you find your partitions. Here’s a blog post of someone who recovered his Mac filesystem with it:


    Needless to say, work on a copy of the data! Unfortunately, it won’t be easy to create partitions in the image file you created. You may have to copy it back to a separate disk.

  8. Ilya Peskov on November 29, 2012 at 2:53 am said:

    Hello, I had similar problem today

    I was able to restore my GPT by booting up with http://gparted.sourceforge.net/ live cd and then using gdisk utility in
    terminal window. First it was asking me what to use: MBR or GPT data structures so I picked GPT then I was poking around and got rid of all my problems that are shown when you use ‘v’ command by deleting boot camp partition. Then reboot and Mac OSX showed up.

    Hope it helps.

  9. Pingback: Backups are overrated | Dalai Felinto

  10. Hello all. gdisk didn’t solve the problem, but fdisk (with some potential help from wiping out the MBR) did.
    Thanks everyone for the help, I’m still in aw for getting it working. Details here: http://www.dalaifelinto.com/?p=708

  11. Hi dude,

    I have landed into the same situation and none of the apple guys are able to help me right now. Can you please help me.

    I am going through the solution link that you have posted as well. But as I have limited background in tech, can you help me out as well?

    Thanks in advance.

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