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I have an Intel MacPro in which I recently installed a new internal 3TB hard disk.

I attempted to format it in Disk Utility using the standard GUID partition map and encountered a strange problem. Disk Utility formatted it using a Logical Volume Group (LVG) instead of GUID.

Furthermore, Disk Utility subsequently refused to allow me to reformat or repartition this drive. The Partition Layout drop-down in Disk Utility is greyed-out. I seem to be stuck with a LVG drive.

Specifics

Model: MacPro Quad Core (Early 2009/Nehalem MacPro4,1)
System: OS X Mountain Lion 10.8.5
Disk Utility: Version 13 (450)
Hard Disk: Seagate Barracuda ST3000DM001 3TB

How can I remove the Logical Volume Group partition scheme and reformat this drive in the GUID standard recommend by Apple?

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  • The only issue I have when doing this is that I can no longer create a bootcamp partition. When I let OS X (10.8) reformat using a logical volume, I have no issues using bootcamp assistant. Only issue is that i have a waisted 800gig logical volume and can no longer create a data partition. If i use the method above and let OS X (10.6) reformat, it lets me using the GUID partition scheme, but when I go to run Boot Camp Assistant, i get the "The startup disk cannot be partitioned or restored to a single partition"... even though it shows I currently have 1 3TB Macintosh HD partition created with
    – user75426
    Apr 11, 2014 at 13:06
  • @g8orballboy I have not used Boot Camp Assistant with this scenario. Are you using Boot Camp Assistant 10.6, or a later version?
    – GrowlTiger
    Apr 11, 2014 at 17:41

1 Answer 1

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This problem has been reported to occur on Intel MacPro's using internal drives from various manufactures with capacities >= 3 TB. Specifically, it's been reported when using Disk Utility in OS X Mountain Lion (10.8) and Mavericks (10.9).

Although there have been solutions involving using diskutil in Terminal posted here at AskDifferent and elsewhere on the web, I found a simpler solution: Format the disk using Disk Utility from an OS X Snow Leopard (10.6) Install DVD.

Warning: This solution will cause you to lose all data on the drive.

  1. Backup any valuable data from the drive in question.
  2. Reboot using the OS X Snow Leopard (10.6) Install DVD. (Hold down the C-Key to boot from the DVD.)
  3. Choose your language (eg. English).
  4. Instead of installing OS X, choose Disk Utility from the Utilities menu.
  5. Select your drive from the pane on the left of the Disk Utility screen.
  6. Choose the Partition tab.
  7. Select your desired Partition Layout.
  8. Select Mac OS Extended (Journaled) under Format:
  9. Check the Options button and verify that GUID is selected as the partition scheme.
  10. Click the Apply button and verify you want to proceed.
  11. When the partition and format process is complete, quit Disk Utility and reboot.

The disk will now be correctly formatted using a GUID partition table.

(If you need to repartition or reformat the drive in the future, you will need to repeat this process. Hopefully Apple will fix this bug in a later version of Disk Utility.)

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