I’m not using boot camp, but my iMac creates an EFI partition after I zero the drive and try to reinstall Catalina

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I’m not using boot camp, but my iMac creates an EFI partition after I zero the drive and try to reinstall Catalina

I have an iMac that I’m trying to format from a recently created USB disk which contains Catalina.

I zero’d the drive using terminal when booting from the USB. The only thing is, when I booted from the USB, used terminal to zero the drive, and went to the GUI for disk utility, for some reason there is a 2gb Catalina System Install which seems to override the USB and it cannot be ejected, unmounted, or erased.

Here is a video to show what is happening: https://vimeo.com/424493885

All I want to do is eliminate the EFI partitions which keep being created when I try to format my hard driveS, even though I’m not using boot camp or trying to Install windows.

I used terminal and the command line prompt to format the USB and create the Catalina install disk, and I just noticed that it has an EFI partition as well.

Is it necessary for my Mac computers and USB drives to have an EFI partition, if I’m not planning on running windows or using boot camp?

iMac Line (2012 and Later)

Posted on May 31, 2020 5:23 AM

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Answer 1

soundboy13 Author

Level 1

5 points

May 31, 2020 5:50 AM in response to dialabrain

Thank you, for some reason everything I was finding about EFI kept leading me back to windows and boot camp.

Now I’d just like to get this computer to boot properly from USB, but that is another question.

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Answer 2

Barney-15E

Level 10

112,800 points

May 31, 2020 5:57 AM in response to soundboy13

Now I’d just like to get this computer to boot properly from USB, but that is another question.

You may want to start a new post specifically about that, but to answer some questions from the video,

The 2GB partition is the Recovery OS.

You'll need to provide a lot more details about what happens when you try to boot from USB. I just skimmed through your video and all it seemed to be was you trying to erase the things you can't.

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