partitioning disk never completes

Question

partitioning disk never completes

I am trying to partition my Mac's disk for Windows 10. 1TB disk, 120GB partition.

Bootcamp assistant runs fine, gets to the disk partitioning and then never completes. The progress bar goes to 100% immediately but the 'Install' button never lights up.

Quitting Bootcamp assistant and running First Aid on the disk from disk utility gives me all my space back.

Here's my setup:

iMac 27" 5K

24GB RAM

1TB fusion drive (~50% used)

MacOS Sierra

iMac (Retina 5K, 27-inch, Late 2014), OS X El Capitan (10.11)

Posted on Sep 29, 2016 4:22 AM

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Answer 1

Loner T

Level 9

59,536 points

Sep 29, 2016 5:39 AM in response to dougmcconnell

Do you have any external disk(s) connected to the iMac? Sierra seems to take much longer to partition then Yosemite or El Capitan did when BC Assistant is used.

As a test, try creating a FAT32 partition of the size you want Windows to be, using Disk Utility and time it. This is who long BC Assistant should take as well.

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Answer 2

Sep 30, 2016 9:04 AM in response to dougmcconnell

The only external disk was the USB drive with the windows image on it, which bootcamp assistant will not let you remove.

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Answer 3

Loner T

Level 9

59,536 points

Sep 30, 2016 9:11 AM in response to dougmcconnell

dougmcconnell wrote:

The only external disk was the USB drive with the windows image on it, which bootcamp assistant will not let you remove.

Are you using the USB both as a source of the Windows Installer and destination for BCA-created Installer? If yes, it will not work.

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Answer 4

Sep 30, 2016 12:53 PM in response to dougmcconnell

I am following the instructions from BCA - insert a USB drive, copy a Windows 10 iso to it, partition the disk and reboot to the USB drive.

I can't get past the partition disk. The funny thing is I did once before but the windows installer didn't like the partition so I removed it and started all over.

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Answer 5

Loner T

Level 9

59,536 points

Sep 30, 2016 4:32 PM in response to dougmcconnell

dougmcconnell wrote:

I am following the instructions from BCA - insert a USB drive, copy a Windows 10 iso to it, partition the disk and reboot to the USB drive.

The ISO is supposed to be on the internal disk. Late 2015 and later Macs do not use a USB Installer, but use an internal partition called OSXRESERVED. Please see https://help.apple.com/bootcamp/assistant/6.0/#/bcmp173b3bf2 as a reference. You can download the appropriate ISO using a wired connection from https://www.microsoft.com/en-us/software-download/home .

I can't get past the partition disk. The funny thing is I did once before but the windows installer didn't like the partition so I removed it and started all over.

Did you remove the partition using BC Assistant or Disk Utility?

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Answer 6

Oct 1, 2016 6:47 AM in response to Loner T

If I run BCA without the USB flash drive connected I get "The installer disc could not be found: Insert your windows installer disc and wait a few seconds for it to be recognized." The partition never actually completed so I used first aid in disk utility to ensure I had all my space back.

It also says pretty clearly next to the checkbox for 'Download the laters Windows support software' : "If you create a Windows 10 or later version install disk from a USB flash drive, the support software is copied to it. Otherwise, you need an external drive formatted as MS-DOS (FAT)."

This is not a late 2015 or later Mac - it is a late 2014 model.

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Answer 7

Loner T

Level 9

59,536 points

Oct 1, 2016 6:55 AM in response to dougmcconnell

On a 2014 model, which of the following screens do you see in BC Assistant? (The language in Sierra is slightly different).

or

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Answer 8

Oct 3, 2016 8:48 AM in response to Loner T

I see the first one - with the three options.

Sent from my iPhone

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Answer 9

Loner T

Level 9

59,536 points

Oct 4, 2016 11:57 AM in response to dougmcconnell

As a test, can you create a FAT32 partition using Disk Utility with the same size that you want Windows installation to be?

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Answer 10

Loner T

Level 9

59,536 points

Oct 4, 2016 12:33 PM in response to Loner T

Just to clarify, are you able to install Windows, since you marked this solved?

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Answer 11

Oct 4, 2016 1:29 PM in response to Loner T

Yes - apparently my reply this morning did not go through. It worked after a fashion. I was able to create a FAT partition. On reboot to install windows, when I selected the EFI disk, the Windows installer would not let me use the partition I created stating that the partition had an MBR partition table and that EFI systems Windows can only be installed to GPT disks.

On a whim, I rebooted and selected the Windows partition (not the EFI/USB disk). Windows installer started and when I tried to install to the new partition it told me that Windows had to be installed to an NTFS disk. So, I clicked 'format' and tried again. Voila! the installation proceeded.

One other strange thing happened: after Windows finished installing and booted up again, the Boot Camp assistant tools started installing automatically. Twice an error window came up saying 'You can't run this app on your PC'. I canceled both times and the install completed and seems to work fine.

Thanks!

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Answer 12

Loner T

Level 9

59,536 points

Oct 4, 2016 2:16 PM in response to dougmcconnell

A 2014 Mac supports both EFI and BIOS mode Windows installations.

EFI is faster than BIOS, because BIOS mode involves simulation BIOS in EFI firmware using a layer called CSM-BIOS (Compatibility Mode). If you delete the MBR using GPT Fdisk, you can use EFI boot.

The error you see is due to choosing EFI Mode when the MBR is present.

If you are happy with the installation, you can leave it as is, or remove it via BCA, and remove the MBR, and re-install EFI-mode Windows on the same partition.

Please remember to back up OSX, Windows and create a Windows System Restore point.

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