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Convert flash drive for Windows 8.1 bootcamp installation from mbr to gpt

Trying to run Windows 8.1 pro x64 on my mid 2010 15" macbook pro. Get stuck during bootcamp installation in Windows because my partition table isn't compatible (MBR but needs to be GPT). My hard drive seems to be Logical partitions/volume etc, while my flash drive was formatted into MBR seemingly by bootcamp, or otherwise not altered into the GPT like it maybe should have.

Generally followed this guide http://www.howtogeek.com/186907/how-to-install-windows-on-a-mac-with-boot-camp/

Steps I took:

Had to use terminal/Xcode to edit info.plist from bootcamp to allow flash drive installation through bootcamp on my mac (removed the "pre" method).

With all three bootcamp options selected, managed to partition the drive

When restarted, my computer had black screen with "no bootable device found".

Restarted again, holding alt/option

Flash drive was now available as one of two options (the other being my standard mac drive)

Windows Setup loaded. Selected language/imputed key/select version etc.

Here is the strange part, the division of the disk does not include "bootcamp" anywhere in the title (like it should according to the guide), and is about 10gb smaller than my partition (assume this is a normal result of windows installation/os files etc). When I try to format the partition, it says I can't, and explains that I can't use MBR, need to use GPT.

Attempted to rewrite disk with Shift F10 Diskpart, list disk, etc, but here it shows drive 0, 1, and 2, (rather than drive 0 partition 1,2,3,4, with 4 being my bootcamp I think). This seems to be a method for installing windows on a windows pc, and I didn't go through with it because I didn't want to loose my mac os yet.

I am not proficient with coding/terminal use, and don't know if there is an option to list partitions etc, so I'm stuck. I can backup my mac and potentially change my partition table etc, but I feel like restoring with time machine would then wipe my existing partition. Is there a workaround I could use? Is there a specific sequence of backups/restores that would work? I'm also okay with manually drag and dropping the files I want back onto a clean slate computer if necessary. Or would simply buying and burning a disc with windows save myself the hassle? Please advise.

Sorry for long question, wanted to get info out right away. Can include more if necessary. Thank you all for your time.

MacBook Pro, OS X Yosemite (10.10), mid 2010 15" Nvidia GeForce 330

Posted on Nov 14, 2014 8:59 AM

Best reply

Loner T

Level 9

59,471 points

Posted on Nov 14, 2014 9:13 AM

Please post the output of following

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

You will need to use Terminal and input your password when prompted. You can triple click on each line and Copy (Command+C) and Paste (Command+V) into the terminal window. Remove any personal information that you do not to be seen on the discussions.

Creating a USB is only part of the problem if your built-in Optical drive is not working. The CSM-BIOS layer used still needs to be configured in the Mac Nvram to boot from USB.

If you have W8.1, which has EFI support, you can try that, but your Mac from 2010 is a preUEFI model, as shown in your Bootcamp info.plist.

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95 replies

Loner T

Level 9

59,471 points

Sep 9, 2015 7:44 PM in response to Jordan Machin

Please see OS X: About OS X Recovery - Apple Support . You also have another option - How to install OS X on an external drive connected to your Mac - Apple Support - which will allow us to boot from an external OSX disk and try to address the issue(s) before you lose data.

Sep 9, 2015 8:01 PM in response to Loner T

Had to format my OS... It was completely blocked. I'm reinstalling Yosemite on my SSD, I don't have SuperDrive anymore... But **** me, I've lost all my files ! But it's not the end of the world, my Mac will be clean..

What's the easier way to install windows 7 on Yosemite ? I have a dvd license, but I repeat, no SuperDrive anymore... And I don't want to make this error again

Loner T

Level 9

59,471 points

Sep 9, 2015 8:10 PM in response to Jordan Machin

Have you replaced your internal Optical drive with another disk, or it is it not working?

Sep 9, 2015 8:18 PM in response to Loner T

Yes it's replaced by a Samsung SSD... So I had a problem with bootcamp but I've fixed it....

Loner T

Level 9

59,471 points

Sep 9, 2015 8:20 PM in response to Jordan Machin

Is everything back to normal, or do you still have problems/issues?

Sep 10, 2015 3:12 AM in response to Loner T

Yes, my Mac runs good... Just have to reinstalling everything ! So, do you have any easy solution to install my windows 7 (on dvd), on my Mac, without the optic drive ?

Thx !

Loner T

Level 9

59,471 points

Sep 10, 2015 5:36 AM in response to Jordan Machin

Please test and see which one works the best for you.

1. Bootcamp without Optical disc drive

2. http://forums.macrumors.com/threads/install-a-windows-7-partition-on-mac-osx-wit hout-optical-drive-or-usb.1836959/#post-20584499

3. You can also try using available NTFS read-write tools to put the installer on the BC partition and try to install directly from the partition.

You may have to temporarily disconnect the second disk.

Sep 10, 2015 7:38 AM in response to Loner T

I'm gonna watch these solutions, thank you ! But I have a question..... I think the problem comes from the bootcamp partition... So, before retry the Windows 7 installation :

- Is it possible to partition THE BOOTCAMP PARTITION, in one partition with the option GUID ?

I didn't try this yesterday !

If not : If I create manually a partition into my SSD for Windows, will this partition be in GUID (and not MBR) by default ?

Loner T

Level 9

59,471 points

Sep 10, 2015 9:49 AM in response to Jordan Machin

Jordan Machin wrote:

- Is it possible to partition THE BOOTCAMP PARTITION, in one partition with the option GUID ?

GUID or MBR is at the whole disk level. On a Mac, Bootcamp is on a GPT disk with a specific disk slice (disk0s4 or disk0s3 depending on OSX version).

If not : If I create manually a partition into my SSD for Windows, will this partition be in GUID (and not MBR) by default ?

Yes, on a Mac all disk slices are GPT. There is a Hybrid MBR created for OSes which do not support GPT (NT, XP, Vista, W7), to allow a BIOS/MBR installation.

On a MacPro tower, if separate physical disks are used, an entire disk can be formatted as MBR disk. On a non-MP Mac (for example a Macbook Pro/Air), OSX uses GPT and a Hybrid MBR allows BIOS emulation.

Sep 10, 2015 10:12 AM in response to Loner T

Ok, I think I understand good... BUT :

I checked my SSD (Lion is installed on it, I'm downloading Yosemite at this time, but it's really low, don't understand why), it's in GUID, I see that when I click on it

I checked my HDD and it's the same, it's in GUID.

Yesterday, when I was trying to install w7 on my bootcamp partition, when I've selected the bootcamp partition I had this message : "Windows cannot be installed to this disk. The selected disk has an MBR partition table. On EFI systems, Windows can only be installed to GPT disks"...

So, rightnow my SSD is on GPT, so if I created a bootcamp partition, will it on GPT or I'll have this message again ?

Are you telling me that I can't install w7 on my macbook pro without the fdisk commands ? I prefer to don't have to use fdisk, I'm not a professionnal, that's why my mac was completly blocked yesterday....

Loner T

Level 9

59,471 points

Sep 10, 2015 12:36 PM in response to Jordan Machin

Here is an example from my Mac...

diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 741.7 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Microsoft Basic Data rMBPBCMP 258.0 GB disk0s4

sudo gpt -vv -r show /dev/disk0

Password:

gpt show: /dev/disk0: mediasize=1000555581440; sectorsize=512; blocks=1954210120

gpt show: /dev/disk0: Suspicious MBR at sector 0

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

gpt show: /dev/disk0: Sec GPT at sector 1954210119

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

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

409640 1448624648 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

1449034288 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

1450303824 1712

1450305536 503904256 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1954209792 295

1954210087 32 Sec GPT table

1954210119 1 Sec GPT header

sudo fdisk /dev/disk0

Disk: /dev/disk0 geometry: 121643/255/63 [1954210120 sectors]

Signature: 0xAA55

Starting Ending

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

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

1: EE 0 0 2 - 25 127 14 [ 1 - 409639] <Unknown ID>

2: AF 25 127 15 - 1023 54 16 [ 409640 - 1448624648] HFS+

3: AB 1023 54 17 - 1023 60 39 [1449034288 - 1269536] Darwin Boot

*4: 07 1023 87 51 - 1023 238 3 [1450305536 - 503904256] HPFS/QNX/AUX

1. My disk is a GPT disk as shown in line 0 - "GUID Partition Scheme".

2. A GPT disk can contain disk slices which are formatted using different file system types (JHFS+, FAT, ExFAT, NTFS,...). disk0s1 is FAT, disk0s2 is JHFS+, disk0s3 is Apple Boot, disk0s4 is NTFS.

3. The GPT shows that the disk is protected by a Protective MBR (Suspicious MBR line).

4. I also have a Hybrid MBR which maps GPT to MBR as shown by the Fdisk output. Windows uses this MBR and uses entry #4 in the MBR as NTFS to boot Windows via Bootcamp.