Clean Install MacOS 12 on M1 Macs with Bootable USB Thumb Drive

[Del Martes]

Thinking ahead here...

Imagine MacOS 12 is released, and I want to do a clean install via a bootable USB thumb drive on my M1 Mac.

Is it really as simple as this Apple Support article details:

Create a bootable installer for macOS - Apple Support

You can use a USB flash drive or other secondary volume as a startup disk from which to install the Mac operating system.

support.apple.com

And the article mentions the USB thumb drive to be formatted as "Mac OS Extended." Why not APFS? Would APFS work?

 

[jdb8167]

It seems to be. I created a USB installer. Booted into recovery and the Reinstall macOS Big Sur said something like install from this booted disk. I didn't actually run the installer though.

 

[Del Martes]

It seems to be. I created a USB installer. Booted into recovery and the Reinstall macOS Big Sur said something like install from this booted disk. I didn't actually run the installer though.

What do you mean? You didn’t install the new OS—whatever yours is?

I should clarify that the new OS has NOT been installed on the M1 Mac yet. The whole new thing, 13 or 15 GB, is on the newly created USB thumb drive.

Also, the support article mentions the USB thumb drive to be formatted as “Mac OS Extended.” Why not APFS?

 

[chrfr]

Thinking ahead here...

Imagine MacOS 12 is released, and I want to do a clean install via a bootable USB thumb drive on my M1 Mac.

Is it really as simple as this Apple Support article details:

Create a bootable installer for macOS - Apple Support

You can use a USB flash drive or other secondary volume as a startup disk from which to install the Mac operating system.

support.apple.com

And the article mentions the USB thumb drive to be formatted as "Mac OS Extended." Why not APFS? Would APFS work?

There's no way of knowing what process would work in the next major macOS release, but it would probably be similar. The process is that simple for macOS 11.

 

[jdb8167]

What do you mean? You didn’t install the new OS—whatever yours is?

I should clarify that the new OS has NOT been installed on the M1 Mac yet. The whole new thing, 13 or 15 GB, is on the newly created USB thumb drive.

Also, the support article mentions the USB thumb drive to be formatted as “Mac OS Extended.” Why not APFS?

I was already at 11.1. I was just experimenting with the boot installer but didn’t want to mess with my working system.

You are right, for some reason the boot installer has to be HFS+. No idea why that limitation but it really doesn’t seem to matter much.

 

[snakes-]

Yesrerday i did the same. 11.1 fresh install from usb. Works fine.
USB drive format to Mac OS Extended. Then this step https://support.apple.com/en-us/HT201372
Firmware update over macos updater and then clean install over usb. This is a bit laborious but the safer way.
I have used the instructions from macworld. https://www.macworld.com/article/3566910/how-to-create-a-bootable-macos-big-sur-installer-drive.html

 

[acidfast7_redux]

macOS 12 coming to you 2040.

Seriously, of all things to worry about.

 

[Del Martes]

macOS 12 coming to you 2040.

Seriously, of all things to worry about.

MacOS 12 was just a prop. What I really had in mind was 11.2. Thanks, guys, for the inputs!

 

[jdb8167]

MacOS 12 was just a prop. What I really had in mind was 11.2. Thanks, guys, for the inputs!

I assumed you just meant to describe an OS update.