Alexbagirian

Q: missing operation system

After updating my Imac to OS X EL Capitan ,  decided to boot in bootcamp, by using alt. But it appeared that the windows icon didn’t show up. After that I looked up on the internet and tried to solve this problem using gdisk. It helped and windows icon appeared in the bootcamp screen. But after I tried booting into windows it just showed MISSING OPERATING SYSTEM.

Can somebody please help to solve this problem?

iMac

Posted on Aug 25, 2016 8:41 AM

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Q: missing operation system

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  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 25, 2016 1:14 PM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 25, 2016 1:14 PM in response to Loner T

    I don't know! But I did not upgrade the computer for a very long time. how I can find it out?

  • by Alexbagirian,Helpful

    Alexbagirian Alexbagirian Aug 25, 2016 2:03 PM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 25, 2016 2:03 PM in response to Loner T

    I don't know! But I did not upgrade the computer for a very long time. how I can find it out?

  • by Loner T,

    Loner T Loner T Aug 25, 2016 4:37 PM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 25, 2016 4:37 PM in response to Alexbagirian

    We need to assume the following partitioning, to allow Windows to come up.

     

    GPT 3 StartGPT 3 SizeGPT 3 EndNTFS StartSector OffsetNTFS SizeNTFS EndSector Offset (MB)NTFS(Gb)Disk EndDisk Difference
    155861424012695361559883776155988377603936378881953521663 -   187.7019535251683505
  • by Loner T,

    Loner T Loner T Aug 25, 2016 4:40 PM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 25, 2016 4:40 PM in response to Alexbagirian

    This requires a bit more work. We will need to create the GPT2, 3, and 4 entries. Do you have a backup of OSX?

  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 12:05 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 12:05 AM in response to Loner T

    Thanks allot for your help. NO, did not find a backup!

  • by Loner T,

    Loner T Loner T Aug 26, 2016 5:13 AM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 26, 2016 5:13 AM in response to Alexbagirian

    Do you have an external disk on which you can back up OS X? We need to change the GPT and a back up would be good to have, in case we run into any issues. You will need an external disk, which is about 1.5 larger than the current size of OS X partition.

  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 6:39 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 6:39 AM in response to Loner T

    Loner Hello. Yes, I did the back up) What do we do next?

  • by Loner T,

    Loner T Loner T Aug 26, 2016 6:45 AM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 26, 2016 6:45 AM in response to Alexbagirian

    I need to be away from a computer for a couple of hours. I will post the detailed steps once I come back to my Mac.

  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 6:47 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 6:47 AM in response to Loner T

    Ok! Great) I will be waiting )

  • by Loner T,

    Loner T Loner T Aug 26, 2016 10:03 AM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 26, 2016 10:03 AM in response to Alexbagirian

    This is non-standard setup. Normally, only the GPT4 entry is manipulated as shown in El Capitan has deleted my bootcamp windows partition .

     

    Install GPT Fdisk (aka gdisk).  Leave your Testdisk display and start a new Terminal Window. You need to use the following steps. If you see any error messages during the following steps, please stop and post back here with the error message. The following steps have values from your Testdisk output (and you can verify) in Steps 7 and 8. Please notice the'+' sign in step 8 (this is called offset notation). The text in parentheses is for informational purpose to describe the action being taken. Gdisk has one-character commands except when entering numbers.

    Rebuild GPT4 using start/end offsets

    1. Sudo gdisk /dev/rdisk0
    2. P  (print the full list of parts)
    3. D (Delete)
    4. 2 (OSX part)
    5. D (Delete)
    6. 3 (Recovery HD)
    7. D  (delete)
    8. 4  (Bootcamp part 4)
    9. N  (new part)
    10. 2  (OSX part 2)
    11. 409640 (Start)
    12. 1558614239 (End - No offset notation)
    13. AF00 (OSX JHFS+)
    14. N (new)
    15. 3 (Recovery HD - Part 3)
    16. 1558614240
    17. +1269536 (End - Offset notation)
    18. AB00 (Recovery HD type)
    19. N (New)
    20. 4 (Bootcamp - Part 4)
    21. 1559883776 ( - Start offset in sectors or the start point for Bootcamp part)
    22. +393637888 ( - Size offset, as opposed to End offset)
    23. 0700 (Windows part type)
    24. P  (print list of all parts just to see what changes will be made)
    25. W (Write the new GPT)
    26. Y  (Yes! really write the new GPT)

    This will delete and re-write the GPT partition info for /dev/disk0s4.


    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 Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 11:06 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 11:06 AM in response to Loner T

    Dear Loner, did as everything above. But still no success. test 1-4 nothing. Tryed to reboot with alt key. Windows window showed up. Pressed it, and it showed BOOTMGR IS MISSING.

  • by Loner T,

    Loner T Loner T Aug 26, 2016 11:09 AM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 26, 2016 11:09 AM in response to Alexbagirian

    Please post the output of

     

    sudo gpt -vv -r show /dev/disk0

    sudo fdisk /dev/disk0

  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 11:14 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 11:14 AM in response to Loner T

    111.png

  • by Loner T,

    Loner T Loner T Aug 26, 2016 11:37 AM in response to Alexbagirian
    Level 7 (23,613 points)
    Safari
    Aug 26, 2016 11:37 AM in response to Alexbagirian

    Does Finder in OSX show any files in the Bootcamp volume?

     

    What is the output of

     

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

  • by Alexbagirian,

    Alexbagirian Alexbagirian Aug 26, 2016 11:44 AM in response to Loner T
    Level 1 (4 points)
    Windows Software
    Aug 26, 2016 11:44 AM in response to Loner T

    No, I dont't see any files. 222.png

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