Previous 1 42 43 44 45 46 Next 1,498 Replies Latest reply: Dec 1, 2015 5:13 PM by Sanjaya83 Go to original post Branched to a new discussion.
  • BrianRandell Level 1 (0 points)

    Christopher Murphy,

    Please see this post if you have a moment.



    Sorry for the extra post and noise.


    Any help appreciated it.



  • Random_Tangent Level 1 (0 points)

    This feels feels more than a little gauche to abuse the reply system like this, but frankly Christopher Murphy, I fear you're my Obi-Wan... my only hope.


    Can you take a look at my FDISK and GPT results and let me know if I've got hope of recovering my Boot Camp MBR?


  • ItIsJustMe Level 1 (0 points)

    I haven't read all 44 pages of this thread so maybe this has been addressed but here's what I'm trying to accomplish.  I run bootcamp and Parallels (the latter using the bootcamp installation as the guest OS) on a 15" rMBP with 256GB SSD.  I use Win8 as the guest OS and Mountain Lion on the host.  I have been trying to enable bitlocker in the guest OS and when I attempt to create another partition (required with bitlocker on a system drive) using the Win8 command:


    BdeHdCfg.exe -target c: shrink -newdriveletter x: -size 1500 -quiet –restart


    I receive the error:


    Disk already has the maximum number of primary and extended partitions. Use the

    '-driveinfo' command for a list of valid target drives.


    This of course is related to the issue originally noted in this thread about hybrid MBR as I already have all four allowed partitions.  It looks like there may be a way around this using some of the techniques described in this thread however rather than creating another partition visible to OSX (which is what OP did) I want to create two partitions visible to Win8.  Would someone be so kind as to walk through how I would accomplish that?


    Thank you!


    Edit: in hopes of increasing the Google-ability of this thread for future people with this issue, Bitlocker Drive Encryption returns the message "Bitlocker Setup could not find a target system drive.  You may need to manually prepare your drive for Bitlocker."  The Event Log contains the following errors in the Bitlocker-DrivePreparationTool log:


    Error Code: 0xC0A00007

    Error Text: BitLocker Setup could not find a target system drive. You may need to manually prepare your drive for BitLocker.




    A volume failed to meet the requirements for a target volume.

    Volume Name: \\?\GLOBALROOT\Device\HarddiskVolume4

    Reason: The system drive cannot be used for the merge operation.

  • Christopher Murphy Level 3 (555 points)

    I don't know exactly how Bitlocker works, but if it's anything like FDE on OS X or Linux, then it requires an unencrypted boot volume (which I think Microsoft weirdly calls a system volume, whereas the much larger system volume with the main OS and application files that ends up being encrypted is called a boot volume). This uncrypted smallish (~100MB) system volume for booting must be a primary partition. I'm pretty sure the Windows boot volume (the big daddy with all files, and is encrypted) can be on an extended partition. However the problem with this is that extended partitions exist in a primary partition. So you need to use one of the primary partitions to define extended partitions, and you need a primary partition to boot from. Yet you only have one primary partition available because Apple uses three primary partitions.


    The Apple hybrid MBR is already a non-standard, ill-advised, flakey, error prone thing. Doing it differently will make it even more non-standard and prone to problems. But if you can avoid using *any* OS X or Windows disk utilities, and understand that major OS upgrades likely will cause the hybrid MBR to be removed causing what appears to be data loss, you might be able to avoid problems and do what you want. But the bottom line is that Apple isn't supporting your use case at all. To do that, they need to support UEFI booting Windows, so that Windows will use the same GPT OS X does, instead of depending on hybrid MBRs.


    You can create a hybrid MBR with its first partition defined by the sectors making up: the GPT itself, EFI System partition, OS X, and Recovery HD, with a type code of 0xEE "GPT Protective partition". So instead of listing out each GPT partition as  separate (and sync'd) MBR partitions, you're going to say the GPT itself and the first three GPT partitions, are defined as one partition in the MBR. Since it's type 0xEE, nothing that understands only MBR should touch those sectors, including Windows.


    Now you have three primary partitions remaining. One of which can be the unencrypted system volume for Windows, and one of which can be the boot volume that's encrypted and contains everything else. It actually leaves you with one primary partition slot available in the MBR which you could make extended partitions from, but in this scenario it isn't needed and isn't advised to combine GPT, MBR primary and extended partitions.


    The thing to keep in mind is you MUST do all of the partition work in advance on the GPT first. You need to get that layout correct in the GPT, and then after all of it's correct, then you make the hybrid MBR from the GPT. And you need to be prepared to make a new hybrid MBR because at any time it seems, something OS X related can nuke that hybrid MBR apparently on a whim. So you'll also need to keep good backups.


    So if you understand all of this, and are prepared procede despite the consequences, namely knowing more about MBR and GPT that you probably want to know, then I suggest posting a new thread and then copying the URL in this thread. This thread is too cluttered to discuss Bitlocker setups. In that thread just summarize what you want to accomplish (a shorter version of what you posted), and also include the result from your current MBR and GPT using commands:

    sudo gpt -r -v show disk0

    sudo fdisk /dev/disk0

  • ItIsJustMe Level 1 (0 points)

    continuing the discussion here:

  • dark fury Level 1 (0 points)

    Hi Christopher Murphy,


    When I use the command - sudo gdisk /dev/disk0

    I get -bash: gdisk: command not found


    Can you please help me on that? I so didn't want to add more and more to this thread but I am helpless at this point.


    Thanks in advance.

  • dark fury Level 1 (0 points)

    Hi Scotch_Brawth,


    The command - sudo gdisk /dev/disk0 returns  -bash: gdisk: command not found


    Can you help me?

  • Christopher Murphy Level 3 (555 points)

    Download and install gdisk.

  • akilbasa Level 1 (0 points)

    Hey guys,


    I couldn't quite wrap my head around the instructions on the first page. Could someone please help me out? Here's what I have: one HDD with 3 partitions: OS X 10.8, Mavericks, and Windows:


    Results for "gdisk of disk0":


    Disk /dev/disk0: 977105060 sectors, 465.9 GiB

    Logical sector size: 512 bytes

    Disk identifier (GUID): A55F90BA-7313-475D-B39E-D1F27D04A0B6

    Partition table holds up to 128 entries

    First usable sector is 34, last usable sector is 977105026

    Partitions will be aligned on 8-sector boundaries

    Total free space is 173377009 sectors (82.7 GiB)


    Number  Start (sector)    End (sector)  Size       Code  Name

       1              40          409639   200.0 MiB   EF00  EFI System Partition

       2          409640       488690887   232.8 GiB   AF00  Customer

       3       488690888       489960423   619.9 MiB   AB00  Recovery HD

       4       662568112       818818111   74.5 GiB    AF00  Mavericks

       5       818818112       820087647   619.9 MiB   AB00  Recovery HD

       6       820856832       977104895   74.5 GiB    0700  WINDOWS

    Result for "sudo gpt -r -vv show disk0":

    gpt show: disk0: mediasize=500277790720; sectorsize=512; blocks=977105060

    gpt show: disk0: PMBR at sector 0

    gpt show: disk0: Pri GPT at sector 1

    gpt show: disk0: Sec GPT at sector 977105059

          start       size  index  contents

              0          1         PMBR

              1          1         Pri GPT header

              2         32         Pri GPT table

             34          6        

             40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

         409640  488281248      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC

      488690888    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

      489960424  172607688        

      662568112  156250000      4  GPT part - 48465300-0000-11AA-AA11-00306543ECAC

      818818112    1269536      5  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

      820087648     769184        

      820856832  156248064      6  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

      977104896        131        

      977105027         32         Sec GPT table

      977105059          1         Sec GPT header

    And lastly, results for "sudo fdisk /dev/disk0":

    Disk: /dev/disk0          geometry: 60821/255/63 [977105060 sectors]

    Signature: 0xAA55

             Starting       Ending

    #: id  cyl  hd sec -  cyl  hd sec [     start -       size]


    1: EE 1023 254  63 - 1023 254  63 [         1 -  977105059] <Unknown ID>

    2: 00    0   0   0 -    0   0   0 [         0 -          0] unused     

    3: 00    0   0   0 -    0   0   0 [         0 -          0] unused     

    4: 00    0   0   0 -    0   0   0 [         0 -          0] unused     


    10.8 and Mavericks partitions work fine, Windows just won't boot. I can still access all the files via working OS's. I just want to restore windows and make it bootable.

    I also have rEFIt installed, not sure if that makes any difference. I hope somebody out there who knows all about this can help me out. I would be very very greatful! Thanks so much

  • Christopher Murphy Level 3 (555 points)

    As you can see from the results, you have six partitions, not three. It's just that three of them aren't visible in the GUI.


    Apple's utilities will not create the required hybrid MBR for Windows when there are more than 4 partitions. So what you want to do is not supported by Apple.


    At risk of present and future data loss, you could use gdisk to create a hybrid MBR with only partition 6 added. That will cause it to make an MBR with partition 1 comprised of GPT partitions 1 through 5. And GPT partition 6 will be defined in the MBR as partition 2. You need to make that partition bootable as well.


    The answer to this question is yes:

    Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N):


    If you make any partition changes at all with Disk Utility, or if it turns out the current or future OS installer tries to fix such unsync'd MBR and GPTs (which I suspect is true based on other reports in these forums), realize that the hybrid MBR will be overwritten with a protective MBR, rendering Windows unbootable again, and you'll need to make a new hybrid MBR with gdisk.


    If you make any partition changes in Windows, realize this will risk totally hosing everythign on the computer because Windows (correctly) only recognizes the hybrid MBR, and will at best not update the GPT at all, and at worst will end up corrupting all or part of it, rendering OS X broken.


    Make use of the gdisk backup option, to keep a copy of the current state of both partition maps should it get messed up in the future.

  • dark fury Level 1 (0 points)

    I am getting this:


    sudo gdisk /dev/disk0


    GPT fdisk (gdisk) version 0.8.7


    Warning: Devices opened with shared lock will not have their

    partition table automatically reloaded!

    Partition table scan:

      MBR: protective

      BSD: not present

      APM: not present

      GPT: present


    Found valid GPT with protective MBR; using GPT.


    Command (? for help):

  • Christopher Murphy Level 3 (555 points)

    You seem to think I know what problem you've having, and therefore I'm somehow able to give you a step by step to fix it. I have no idea what you're trying to accomplish. The result you've posted is completely normal expected behavior when running gdisk.

  • dark fury Level 1 (0 points)

    In the first page you had mentioned:


    sudo gdisk /dev/disk0


    If you get any error messages at this point, report the error messages, don't proceed further.


    I do get it that this is a warning prompt. I just wanted to check with you if I am not doing anything wrong. Thanks.

  • dark fury Level 1 (0 points)

    @Christopher Murphy,


    I am able to boot into Windows now. Thank you so much You are really awesome. I wish I could return you the favour. Not many take their time off and help people with such complex issues. Thanks again. I will be posting a detailed note on each and every step that I have followed, later.


    By the way, where did gdisk install, on Mac, if I want to uninstall it? Thank again and again

  • GregoryBL Level 1 (0 points)

    Christopher Murphy,


    Could I trouble you to take a look at my thread?



    Thank you in advance.

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