Can't erase my external hard drive (problems with hard drive after updating OS to Catalina)

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Can't erase my external hard drive (problems with hard drive after updating OS to Catalina)

I have a 5TB external drive, I updated my OS to Catalina earlier this week and when I put the ext drive back in it said the disk "couldn't be repaired" and that I needed to reformat it. After many hours backing up the 3.5TB of data I had on there, I finally went to Disk Utility and selected to erase the entire disk, I reformatted to MS-DOS (although I think this is what it was originally). This completed fine, according to the dialog box, but after clicking 'Done' it seems like the disk was partitioned, it now has 4.4TB used and I can't get it to erase this data, no matter how many times I ask it to erase it stays there, I went into the partition tab, but it won't let me remove the partitions - the plus/minus buttons. I just want a clean drive again and there doesn't seem to be any way of doing this.The drive wasn't even attached to the computer when I updated the OS so I don't understand how this has happened.

I've attached screenshots in case that's helpful to anyone, the drive I want to erase is called THE BRAIN.

MacBook Pro 15", macOS 10.15

Posted on Jan 14, 2020 9:44 AM

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Answer 1

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Kappy

Level 10

361,765 points

Jan 14, 2020 2:01 PM in response to TheGlowBox

Why is this drive formatted for MSDOS? Are you using it on a Windows machine? If not, then you need to reformat it:

Drive Preparation - El Capitan or Later

Open Disk Utility in the Utilities' folder.
After Disk Utility loads select the drive (out-dented entry with the model info and size) from the side list.
Click on the Erase button in the Disk Utility toolbar. A panel should drop down.
In the drop down panel set the partition scheme to GUID. Set the Format type to Mac OS Extended (Journaled.)
Click on the Apply button and click on the Done button when it is activated.
Quit Disk Utility.

See if this helps.

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Answer 2

TheGlowBox Author

Level 1

12 points

Jan 14, 2020 2:12 PM in response to Kappy

Hi, I just reformatted to Mac OS Extended (Journaled.) as you suggested and it has rectified the problem, thank you. It was originally formatted to MSDOS because I migrated from a PC when I bought my Mac and thought I might need to go back and forth between the two if I had problems (I did), but it's only very occasionally now and I can use other workarounds like Dropbox etc, so I don't mind.

I suppose it would be interesting to know if there would have been a fix if I still needed to go between them on the same level, but thank you for this in any case.

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Can't erase my external hard drive (problems with hard drive after updating OS to Catalina)

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