Q: Windows 8.1 install on iMac with fusion drive, GPT partition error

Please download GPT Fdisk from http://sourceforge.net/projects/gptfdisk/ . 

Can you post the output of the following Terminal commands?

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk1

sudo fdisk /dev/disk1

The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.

Please use GPT Fdisk (gdisk) to execute the following steps and test.

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.

1. Sudo gdisk /dev/disk1
2. P  (Print list of parts)
3. R  (Recover)
4. H (chooses Hybrid)
5. O (print current Hybrid MBR)
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): N

This looks good. Please retry your Windows installation.

Hi Loner

I have been trying to install Windows 8.1 all day and have just found this thread. Have a 27"iMac 5k with 3Tb fusion drive and have been getting the GPT errors.

I followed your terminal instructions, but I got unexpected messages when i entered "h" then 2 3 4

Here is the output  from Terminal :

Recovery/transformation command (? for help): h

WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,

just hit the Enter key at the below prompt and your MBR partition table will

be untouched.

Type from one to three GPT partition numbers, separated by spaces, to be

added to the hybrid MBR, in sequence: 2 3 4

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

GPT partition #2 does not exist or is too big; skipping.

GPT partition #3 does not exist or is too big; skipping.

GPT partition #4 does not exist or is too big; skipping.

No partitions converted; original protective/hybrid MBR is unmodified!

Recovery/transformation command (? for help): n

b use backup GPT header (rebuilding main)

c load backup partition table from disk (rebuilding main)

d use main GPT header (rebuilding backup)

e load main partition table from disk (rebuilding backup)

f load MBR and build fresh GPT from it

g convert GPT into MBR and exit

h make hybrid MBR

i show detailed information on a partition

l load partition data from a backup file

m return to main menu

o print protective MBR data

p print the partition table

q quit without saving changes

t transform BSD disklabel partition

v verify disk

w write table to disk and exit

x extra functionality (experts only)

? print this menu

Recovery/transformation command (? for help): n

b use backup GPT header (rebuilding main)

c load backup partition table from disk (rebuilding main)

d use main GPT header (rebuilding backup)

e load main partition table from disk (rebuilding backup)

f load MBR and build fresh GPT from it

g convert GPT into MBR and exit

h make hybrid MBR

i show detailed information on a partition

l load partition data from a backup file

m return to main menu

o print protective MBR data

p print the partition table

q quit without saving changes

t transform BSD disklabel partition

v verify disk

w write table to disk and exit

x extra functionality (experts only)

? print this menu

Recovery/transformation command (? for help): y

b use backup GPT header (rebuilding main)

c load backup partition table from disk (rebuilding main)

d use main GPT header (rebuilding backup)

e load main partition table from disk (rebuilding backup)

f load MBR and build fresh GPT from it

g convert GPT into MBR and exit

h make hybrid MBR

i show detailed information on a partition

l load partition data from a backup file

m return to main menu

o print protective MBR data

p print the partition table

q quit without saving changes

t transform BSD disklabel partition

v verify disk

w write table to disk and exit

x extra functionality (experts only)

? print this menu

Recovery/transformation command (? for help): o

Disk size is 5860533168 sectors (2.7 TiB)

MBR disk identifier: 0x00000000

MBR partitions:

Number  Boot  Start Sector   End Sector   Status      Code

   1                     1   4294967294   primary     0xEE

Recovery/transformation command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING

PARTITIONS!!

Do you want to proceed? (Y/N): y

OK; writing new GUID partition table (GPT) to /dev/disk1.

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Warning: The kernel may continue to use old or deleted partitions.

You should reboot or remove the drive.

The operation has completed successfully.

From

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk1

sudo fdisk /dev/disk1

I now get :

diskutil list

/dev/disk0

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *121.3 GB   disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:          Apple_CoreStorage                         121.0 GB   disk0s2

   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3

/dev/disk1

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *3.0 TB     disk1

   1:                        EFI EFI                     209.7 MB   disk1s1

   2:          Apple_CoreStorage                         2.3 TB     disk1s2

   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3

   4:       Microsoft Basic Data BOOTCAMP                700.9 GB   disk1s4

/dev/disk2

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:                  Apple_HFS Macintosh HD           *2.4 TB     disk2

                                 Logical Volume on disk0s2, disk1s2

                                 51210933-CA61-4132-99DA-14284FB36473

                                 Unencrypted Fusion Drive

Wherry-iMac:~ Wherrys$ diskutil cs list

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group 04F51976-32DF-4C3F-9296-6ADADC7EEBAA

    =========================================================

    Name:         Macintosh HD

    Status:       Online

    Size:         2419855843328 B (2.4 TB)

    Free Space:   376832 B (376.8 KB)

    |

    +-< Physical Volume D5D20091-CCC3-48F2-85F9-0207EFE7304A

    |   ----------------------------------------------------

    |   Index:    0

    |   Disk:     disk0s2

    |   Status:   Online

    |   Size:     120988852224 B (121.0 GB)

    |

    +-< Physical Volume A6AD4A38-FCA2-4543-9CD8-5525D9C2639F

    |   ----------------------------------------------------

    |   Index:    1

    |   Disk:     disk1s2

    |   Status:   Online

    |   Size:     2298866991104 B (2.3 TB)

    |

    +-> Logical Volume Family 2B272C20-609F-42F6-AB2E-219AEE481B7E

        ----------------------------------------------------------

        Encryption Status:       Unlocked

        Encryption Type:         None

        Conversion Status:       NoConversion

        Conversion Direction:    -none-

        Has Encrypted Extents:   No

        Fully Secure:            No

        Passphrase Required:     No

        |

        +-> Logical Volume 51210933-CA61-4132-99DA-14284FB36473

            ---------------------------------------------------

            Disk:                  disk2

            Status:                Online

            Size (Total):          2414000209920 B (2.4 TB)

            Conversion Progress:   -none-

            Revertible:            No

            LV Name:               Macintosh HD

            Volume Name:           Macintosh HD

            Content Hint:          Apple_HFS

Wherry-iMac:~ Wherrys$ sudo gpt -vv -r show /dev/disk1

gpt show: /dev/disk1: mediasize=3000592982016; sectorsize=512; blocks=5860533168

gpt show: /dev/disk1: PMBR at sector 0

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: Sec GPT at sector 5860533167

       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  4489974592      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC

  4490384232     1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

  4491653768        1400        

  4491655168  1368877056      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

  5860532224         911        

  5860533135          32         Sec GPT table

  5860533167           1         Sec GPT header

Wherry-iMac:~ Wherrys$ sudo fdisk /dev/disk1

Disk: /dev/disk1 geometry: 97451/255/63 [1565565872 sectors]

Signature: 0xAA55

         Starting       Ending

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

------------------------------------------------------------------------

1: EE 1023 254  63 - 1023 254  63 [         1 - 4294967294] <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     

Wherry-iMac:~ Wherrys$

Any help you could give would be much appreciated!

Cheers

Also:

sudo gpt -vv -r show /dev/disk1

gpt show: /dev/disk1: mediasize=3000592982016; sectorsize=512; blocks=5860533168

gpt show: /dev/disk1: PMBR at sector 0

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: Sec GPT at sector 5860533167

       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  4489974592      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC

  4490384232     1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

  4491653768        1400        

  4491655168  1368877056      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

  5860532224         911        

  5860533135          32         Sec GPT table

  5860533167           1         Sec GPT header

Wherry-iMac:~ Wherrys$ sudo fdisk /dev/disk1

Disk: /dev/disk1 geometry: 97451/255/63 [1565565872 sectors]

Signature: 0xAA55

         Starting       Ending

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

------------------------------------------------------------------------

1: EE 1023 254  63 - 1023 254  63 [         1 - 4294967294] <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     

Wherry-iMac:~ Wherrys$ sudo gpt -vv -r show /dev/disk0

Password:

gpt show: /dev/disk0: mediasize=121332826112; sectorsize=512; blocks=236978176

gpt show: /dev/disk0: PMBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 236978175

      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  236306352      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC

  236715992     262144      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

  236978136          7        

  236978143         32         Sec GPT table

  236978175          1         Sec GPT header

Wherry-iMac:~ Wherrys$ sudo fdisk /dev/disk0

Disk: /dev/disk0 geometry: 14751/255/63 [236978176 sectors]

Signature: 0xAA55

         Starting       Ending

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

------------------------------------------------------------------------

1: EE 1023 254  63 - 1023 254  63 [         1 -  236978175] <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

Jake Wherry can you post a new discussion (same request on the other thread as well).

Ok Loner, I've put  a new post up

Will this work for El Capitan and Windows 10?

I'm got a MBP with a "home made" Fusion Drive (500gb Apple SSD, and 2TB HD, Fused together).

Been banging my head against the wall trying to get Boot Camp and Win 10 to work together, and the last thing I want to do is screw-up my OSX Partition.

Thanks in Advance!!!

Please start a new discussion, and post the year/model of your Mac (not the serial number), and the output of the following commands on the new discussion

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.

Loner T, Thank you!

Per your request, here is my post and info: Windows 10 install on MacBook Pro with fusion drive, GPT partition error

Thanks in advance!!!!

I had the same problem with 3TB fusion drive until i found this link: https://www.27partners.com/2012/12/how-to-install-boot-camp-on-a-3tb-fusion-driv e-mac/

I was able to successfully install Windows 10 on my iMac 5K.