
If your USB thumb drive, USB external disk or flash storage contains a usable operating system or a macOS installer, you can select it at boot time using macOS’ built-in feature called Startup Manager, which can be invoked via a simple keystroke.Ģ) Press and hold the Option key immediately upon hearing the startup chime. How to start up your Mac from an external USB storage device Tip: You can easily burn a bootable image of macOS to a DVD using Disk Utility. You can also press the left mouse button on a wired mouse during startup to open the disc tray.

Your Mac should start up from the macOS installer CD/DVD media. How to start up your Mac from a bootable CD/DVDġ) Firstly, turn on your Mac, or restart it if it’s already on by choosing Restart in the Apple menu.Ģ) Secondly, press and hold the C key on your keyboard immediately upon hearing the startup chime.

Bootable optical media (CD or DVD) on Macs equipped with Apple’s Super Drive or a USB thumb drive formatted with a GUID partition type and containing a macOS installer or a usable operating system.Īpple advises against booting from external storage containing a version of macOS earlier than the one your Mac shipped with.

Starting up your Mac from an external disk requires the following:
