Boot Camp: This disk appears to have been partitioned by another utility. It must be erased before installing Windows.

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Level 1

18 points

Boot Camp: This disk appears to have been partitioned by another utility. It must be erased before installing Windows.

I have a 6TB SATA Western Digital Drive on my 2012 Mac Pro. I thought 'what better place to put a bootcamp partition'? But when I went to use the Boot Camp Assistant I was greeted with this:

Boot Camp: This disk appears to have been partitioned by another utility. It must be erased before installing Windows.

I thought 'OK - I'll remove data.. use Disk Utility to erase the drive completely and try again. After a few hours I used Disk Utility.. completely repartitioned the drive and tried again.

Same message.

It appears for whatever reason I can either completely erase and use the entire drive for Windows (blah) or I have to use another drive or not use Boot Camp at all. Is there an issue with the size of hard drive that Boot Camp can support? Any advice?

Mac Pro, OS X El Capitan (10.11.5), Mac Pro 2012 Model

Posted on Jul 4, 2016 8:44 AM

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Answer 1

chris_g1

Community Specialist

Jul 5, 2016 7:53 AM in response to ElPapa

Hello ElPapa,

Thank you for using Apple Support Communities.

I understand that you want to put a Boot Camp partition on your Western Digital HD connected to your Mac Pro. Is this your startup drive? If not, this might be part of your problem. According to the following article on installing Microsoft Windows using Boot Camp, it says that you need "At least 55 GB of free disk space on your startup drive".

How to install Windows using Boot Camp

If you are installing it on your startup drive and still getting this message, take a look at this article: Boot Camp: Partition alert message when using Boot Camp Assistant

Best regards.

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Answer 2

ElPapa Author

Level 1

18 points

Jul 5, 2016 8:01 AM in response to chris_g1

In order:

Yes it's Western Digital

No It's my startup drive

Yes I have more than 55GB on the start up drive (in fact I have about 900GB available on the startup drive).

No that's not the problem because I've put Windows on a Boot Camp partition on a non-boot volume on this very machine in the past (just with different drives).

This article doesn't help because it's not applicable to the new Disk Utility - and there are no other partitions on the drive, anyway.

Boot Camp: Partition alert message when using Boot Camp Assistant - Apple Support

From DiskUtil

/dev/disk2 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *6.0 TB disk2 1: EFI EFI 209.7 MB disk2s1 2: Apple_HFS UserData 6.0 TB disk2s2

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Answer 3

ElPapa Author

Level 1

18 points

Jul 5, 2016 7:48 PM in response to chris_g1

chris_g1

I meant to say "No it's NOT my startup drive".

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Answer 4

ElPapa Author

Level 1

18 points

Jul 12, 2016 2:49 PM in response to chris_g1

Anyone / Everyone..

Could the issue be that we simply still can't install Windows using Bootcamp to a drive larger than 2TB?

Could Bootcamp be simply not stating the correct error for this problem?

https://www.twocanoes.com/support/winclone/installing-windows-via-boot-camp-on-a -large-(2.2-tb-or-larger)-drive-in-lion-(10.7)-and-later

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Answer 5

Loner T

Level 9

59,536 points

Jul 12, 2016 5:58 PM in response to ElPapa

On a 2012 MP, Windows 7/8.1 can be installed. It requires all storage which is not needed to be physically removed from SATA bays, for example Bay 3 in your case.

You will need to manually partition the 6TB disk and use the first 2 TB to install Windows. The remainder of the drive can be used for OS X. You will also need to create a MBR manually which will 'hide' the disk outside the 2TB boundary.

The other option is to find a 2TB disk and install Windows on it.

Your MP does not officially support EFI booting of Windows, even though it uses EFI 1.1 for OS X.

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Answer 6

ElPapa Author

Level 1

18 points

Jul 12, 2016 6:02 PM in response to Loner T

Hey LT,

Thank you for this information. This basically coincides with the twocanoes blog. Could you point me at information elaborating on the statement "Your MP does not officially support EFI booting of Windows"? I presume that the 2013 Mac Pro does an EFI boot of windows where there's some 'hack' to accommodate booting Windows on earlier Mac pro models?

As far as the fix.. I did work around my problem by setting up a partition on a 2TB volume as you mentioned.

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Answer 7

Loner T

Level 9

59,536 points

Jul 12, 2016 8:42 PM in response to ElPapa

UEFI 2.0 was first implemented on the Late 2013 Macs. The previous models support Windows using a Hybrid MBR which maps the GPT to a MBR.

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Answer 8

ElPapa Author

Level 1

18 points

Jul 12, 2016 8:42 PM in response to Loner T

OK.. so the I knew about the hybrid GPT/MBR system.. I did not know it was replaced. That also explains why there's the limit (because of the MBR and how large a drive it can access).

Thank you for the insights. They were most helpful.

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Answer 9

Loner T

Level 9

59,536 points

Jul 13, 2016 7:31 AM in response to ElPapa

MBRs will typically support 2TB disks with 512-byte sectors. 4K sectors can support larger disks, with 32-bit sector addresses.

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