cmcqueen

Q: Missing operating system Macintosh partition

Trying to install Windows 7 partition using .iso.

errors "startup repair cannot repair this computer automatically" / couldn't find the drivers.

In system repair i set the active partition to the 200MB "partition 2".

Restarted the computer holding alt and the Windows partition no longer shows up. Booted to macintosh and it says "missing operating system"

 

Freaking out as I can't boot into either partition now. Help!

MacBook Pro with Retina display, OS X El Capitan (10.11)

Posted on Jan 20, 2016 4:42 PM

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Q: Missing operating system Macintosh partition

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  • by Loner T,

    Loner T Loner T Jan 20, 2016 5:03 PM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 20, 2016 5:03 PM in response to cmcqueen

    The 200MB partition is your Mac EFI. Please install OS X on an external disk - How to install OS X on an external drive connected to your Mac - Apple Support .

     

    What year/model is your Mac?

  • by cmcqueen,

    cmcqueen cmcqueen Jan 20, 2016 5:13 PM in response to Loner T
    Level 1 (0 points)
    Jan 20, 2016 5:13 PM in response to Loner T

    2014 MacBook retina

  • by cmcqueen,

    cmcqueen cmcqueen Jan 20, 2016 5:25 PM in response to Loner T
    Level 1 (0 points)
    Jan 20, 2016 5:25 PM in response to Loner T

    Installing OSX on the external drive. What should I do once it's installed? Thanks!

  • by Loner T,

    Loner T Loner T Jan 20, 2016 5:32 PM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 20, 2016 5:32 PM in response to cmcqueen

    Boot from it, and install GPT Fdisk - http://sourceforge.net/projects/gptfdisk/ . We need to inspect the internal disk and see of we can revive the disk. Choosing the 200MB is most likely the cause. It would also have turned the disk into an MBR disk, and OS X will not boot from an MBR disk.

  • by cmcqueen,

    cmcqueen cmcqueen Jan 20, 2016 9:02 PM in response to Loner T
    Level 1 (0 points)
    Jan 20, 2016 9:02 PM in response to Loner T

    I've installed GPT Fdisk. What should I do next?

  • by Loner T,

    Loner T Loner T Jan 21, 2016 5:22 AM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 21, 2016 5:22 AM in response to cmcqueen

    If you have booted from it, can you post the output of

     

    diskutil list

    sudo gpt -vv -r show /dev/disk0

    sudo gdisk /dev/disk0

     

    If Gdisk prompts with any questions, please post a screen shot/text output.

  • by cmcqueen,

    cmcqueen cmcqueen Jan 21, 2016 8:25 AM in response to Loner T
    Level 1 (0 points)
    Jan 21, 2016 8:25 AM in response to Loner T

    Screen Shot 2016-01-21 at 8.15.11 AM.png

    Also, if it makes a difference, this computer is running 10.9.5

  • by Loner T,

    Loner T Loner T Jan 21, 2016 8:35 AM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 21, 2016 8:35 AM in response to cmcqueen

    1. What is /dev/disk2?

    2. /dev/disk1 looks like your external boot.

    3. Please post the output of

         sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

         sudo fdisk /dev/disk0

    4. Can you run the following two procedures and try the Alt/Option method to check available selections?

         Resetting the System Management Controller (SMC) on your Mac - Apple Support

         How to Reset NVRAM on your Mac - Apple Support

  • by cmcqueen,

    cmcqueen cmcqueen Jan 21, 2016 8:58 AM in response to Loner T
    Level 1 (0 points)
    Jan 21, 2016 8:58 AM in response to Loner T

    1. I don't know what /dev/disk2 is, I don't have any other externals connected. 
    2. Yes, /dev/disk1 is my external boot.

    3.

    Screen Shot 2016-01-21 at 11.51.33 AM.png

    4. Running those now, will post outcome

  • by Loner T,

    Loner T Loner T Jan 21, 2016 9:56 AM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 21, 2016 9:56 AM in response to cmcqueen

    In the Fdisk output, if you notice, the "*" is on entry 1. It should be on entry 4. This is why tour Windows is unbootable. This can be corrected using Gdisk, that you have installed.

     

    Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see the sample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers. Please see the sample Q&A before you execute these steps.

    1. Sudo gdisk /dev/rdisk0
    2. P  (Print list of parts)
    3. R  (Recover)
    4. O (print current Hybrid MBR)
    5. H (chooses Hybrid)
    6. Partitions numbers to be hybridized: 2 3 4
    7. Y  (Good for GRUB question)
    8. N  (part 2 boot flag)
    9. N  (part 3 boot flag)
    10. Y  (part 4 boot flag make NTFS bootable partition)
    11. O  (print current Hybrid MBR)
    12. W (Write the new MBR)
    13. Y (Yes! write the new MBR)
    14. Reboot

     

    Here is sample Q&A for this section. Please notice the Press Enter/Return.

     

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

     

    Creating entry for GPT partition #2 (MBR partition #2)

    Enter an MBR hex code (default AF): Press Enter/Return

    Set the bootable flag? (Y/N): N

     

    Creating entry for GPT partition #3 (MBR partition #3)

    Enter an MBR hex code (default AB): Press Enter/Return

    Set the bootable flag? (Y/N): N

     

    Creating entry for GPT partition #4 (MBR partition #4)

    Enter an MBR hex code (default 07): Press Enter/Return

    Set the bootable flag? (Y/N): Y

     

    Test 1 - Does Bootcamp Volume show up in Finder?

    Test 2 - Can you see files in Bootcamp Volume?

    Test 3 - Can you select Bootcamp in System Preferences -> Startup Disk?

    Test 4 - If Test 3 is successful, select Bootcamp and Click Restart.

  • by cmcqueen,

    cmcqueen cmcqueen Jan 21, 2016 6:37 PM in response to Loner T
    Level 1 (0 points)
    Jan 21, 2016 6:37 PM in response to Loner T

    Yes to the first 3 questions.
    Bootcamp drive is called "Untitled."

    When I selected bootcamp as the startup disk and rebooted, screen appeared "windows failed to start. a recent hardware or software change might be the cause. Insert your windows installation disk and restart your computer."
    However, bootcamp had me set up a flash drive using an .iso file. As you know I'm on a MacBook retina, no disk drive. However I have the superdrive connected with a windows disk. Same screen appeared after restarting this way.

  • by Loner T,

    Loner T Loner T Jan 21, 2016 6:44 PM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 21, 2016 6:44 PM in response to cmcqueen

    Be careful repairing W7 using a BCA-created USB that was created under El Capitan. Can you check Product Version on the BCA-created USB Installer?

  • by cmcqueen,

    cmcqueen cmcqueen Jan 21, 2016 6:49 PM in response to Loner T
    Level 1 (0 points)
    Jan 21, 2016 6:49 PM in response to Loner T

    Product version of BCA that I used to create USB is 5.1.4. Is that what you mean?

    I'm sorry I was wrong I'm fixing my friends computer here and it's running Yosemite 10.10.5

  • by Loner T,

    Loner T Loner T Jan 21, 2016 6:57 PM in response to cmcqueen
    Level 7 (23,598 points)
    Safari
    Jan 21, 2016 6:57 PM in response to cmcqueen

    On the USB, there is a Bootcamp.xml file, there is a line with Product Version that we should check.

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