How to Boot Your Mac from an External Boot Disk: A Step-by-Step Guide 'bootable disk utility mac'

Booting your Mac from an external boot disk can be a useful trick for troubleshooting or recovering data from a failed hard drive. However, Apple's T2 chip and Apple Silicon (M1) architecture have introduced some changes that make the process slightly more complicated. In this article, we'll walk you through the steps to boot your Mac from an external boot disk.

For Intel Macs with a T2 Chip

If you're using an Intel Mac with a Touch Bar or Touch ID, you'll need to follow these additional steps:

1. Power on your Mac and hold down the power button until you see the startup options screen.

2. Select the external drive you want to start your Mac from and choose Continue.

3. Under the External Boot section of the Startup Security Utility, check the box for 'Allow booting from external media' to prevent boot restrictions.

For Apple Silicon (M1) Macs

Booting an M1 Mac from an external drive is different from Intel Macs. To do so:

1. Power on your Mac and hold down the OPTION key to load the boot menu.

2. Choose an external disk from the boot menu.

3. Reboot your Mac again, holding the OPTION key to boot from a boot disk should work now.

Why Can't My Mac Boot From an External Drive?

If you're finding that your Mac won't boot from an external drive, it may be due to the security feature on T2 Macs being enabled. This setting prevents your computer from booting when a USB boot disk or other boot media is used. To disable this feature:

1. Pull down the Utilities menu and choose 'Startup Security Utility.'

2. Reboot your Mac, then immediately hold Command + R keys to load into Recovery Mode.

By following these steps, you should be able to successfully boot your Mac from an external drive.

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