Reinstalling macOS Monterey on MacBook Pro M1

[iphonefreak450]

First off, I don’t need to reinstall macOS on my MBP M1 but in case something happens, then how can I reinstall macOS from the Disk Utility under the Recovery Mode?

I see two disk volumes . Macintosh HD and Macintosh-Data?

If I want to Erase or wipe all of my data, then which one should I erase?
Both the Macintosh HD or only the Macintosh HD -Data?

Recently I just updated to Monterey 12.6.

If I erase both, would that rollback to the older version of Monterey which was 12.3?

I searched all around the web and some say to erase both HDs and some say to only leave the HD-Data.

Where can locate the Apple’s official macOS reinstall tutorial to reinstall macOS using the Disk Utility from the Recovery Mode?

And is it true that the reinstall can take 12 hours?

 

[Mike Boreham]

First off, I don’t need to reinstall macOS on my MBP M1 but in case something happens, then how can I reinstall macOS from the Disk Utility under the Recovery Mode?

I see two disk volumes . Macintosh HD and Macintosh-Data?

If I want to Erase or wipe all of my data, then which one should I erase?
Both the Macintosh HD or only the Macintosh HD -Data?

Recently I just updated to Monterey 12.6.

If I erase both, would that rollback to the older version of Monterey which was 12.3?

I searched all around the web and some say to erase both HDs and some say to only leave the HD-Data.

Where can locate the Apple’s official macOS reinstall tutorial to reinstall macOS using the Disk Utility from the Recovery Mode?

And is it true that the reinstall can take 12 hours

If you want to erase all your data and start again from factory state, use "Erase all Content and settings". No need to use Disk Utility to erase anything.

Many people think they need to do a "fresh install", by which they mean delete the existing System Volume and install a fresh one without any "cruft". This has no value since Apple introduced the locked signed sealed separate system volume. This is checked extremely tightly every boot and if it passes, a snapshot is made and the machine boots from the snapshot.

There is no "cruft" from earlier installs in the System volume. Every tiny thing you do or add, including all apps, data, prefs and settings is incorporated in the -Data volume. If the machine boots, the System Volume is totally unmodfied and the same as a freshly downloaded one. If it fails verification you are told to reinstall and the machine won't boot.

The only time you would use Disk Utility to erase anything would be if you want to change the OS to a different version.

I have never had an install take 12 hours. If you do reinstall macOS from Recovery it has to download it so time will depend on internet.

 

[iphonefreak450]

Okay 👍 thanks. Then I’ll just use the Erase all Contents and Settings.