MacOS – How to format a Seagate HDD to OS X Extended (Journal) with Disk Utility

If you do not care about loosing the data already on it, try changing the partition scheme instead of formatting it.

Select the drive like in your screen shot, then click on Partition tab on the right, then select 1 partition from the pop-up menu on top of the graph. Then click Options at the bottom and select GUID (the first option) in the next window, close it, and then click Apply in the main window. You can also set the format of the partition before you click apply. It should already have selected Mac OS Extended. All this assumes of course that you wish to use this drive with a Mac and only a Mac… if you want to use it on a PC and a Mac, you'll have to select other options, but still possible.

If that still doesn't work, it's probable the drive is physically damaged.

What you have right now is a Windows Partition scheme and a FAT formatted partition. I could be mistaken, but I think FAT32 does not work on OS X. I'm only 50% sure though...

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.)