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Unable to partition external hard drive on Mac using Mojave

I have erased and reformatted several times, but partition in Disk Utilities continues to be greyed out. I have even tried different Macs with Mojave. I have other external drives partitioned, and First Aid doesn't show anything wrong with the external drive. I am really at a loss.


Posted on May 26, 2019 12:50 PM

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5 replies

May 27, 2019 3:16 PM in response to we04ndy

Select the KESU USB 3.0 Media as you have highlighted in the screen shot. Click on Erase in the top tool bar. Select macOS Extended( Journaled) with a GUID Partition Map Scheme (not Master Boot Record) as your screenshot shows. Click on Erase at the lower left of the drop down box. When it is finished, the Partition button should be solid colored and no longer greyed out. Click on the Partition button and the partition drop down box should show Partition the drive as you wish.


May 26, 2019 1:16 PM in response to we04ndy

Change the View dropdown menu in the toolbar to Show all Devices, then take another snap of EXTERNAL. You cannot partition the drive because you have formatted it which creates a new volume. It's that new volume that you can partition. If you did everything as default, then the new volume should be named, "Untitled." If you select that volume in the new View, then you can partition it.

Unable to partition external hard drive on Mac using Mojave

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