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geoffs1 Author

Level 1

8 points

formatting 1Tb external hard disk

when i try to format a new 1Tb external hard disk from my MacBook Air running Mojave, i get an "unable to write last block" error.

How do i solve this

Posted on Aug 22, 2019 8:42 AM

Top-ranking reply

fuzzymo

Level 4

2,036 points

Posted on Aug 22, 2019 10:36 AM

Open Disk Utility (in the Applications Folder/ Utilities folder). In the upper left of the Disk Utility window, click on "View". Then select "Show All Devices". Now you should see your new drive in the disk Utility sidebar. Click on the device, not the volume below it. Click on "Erase" in the tool bar. Select the Scheme, then select the Format. I don't know what you intend to use this drive for. If you are using it for Mac only, choose Scheme: GUID Partition Map, Format: Either MacOS Extended (Journaled) or APFS. Choose Format: ExFAT if you are going to use it for both Mac and Windows. Click on "Erase" at the lower left of the dropdown window. Let Disk Utility finish.

Welcome to Disk Utility on Mac - Apple Support

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formatting 1Tb external hard disk

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