You set your Mac or Macbook which disk to start up from when more than one startup disk is connected. This works for USB drives including the NinjaStik

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For 2018 to 2020 Macs with the Secure Boot T2 Chip, see the 2020 Macbook Pro Boot from USB instructions.

A “startup disk” is a volume or partition of a drive that contains a bootable operating system.

You can set your Mac to automatically use a specific startup volume, or you can temporarily override this choice at startup.

1. From the Apple menu choose System Preferences.
2. Click the Startup Disk icon in System Preferences, or choose View > Startup Disk.
3. Select your startup disk from the list of available volumes.

The next time you start up or restart your computer, your Mac starts up using the operating system on the selected volume.

Temporarily change your startup disk with Startup Manager

Startup Manager allows you to pick a volume to start from while the computer is starting up.

Use these steps to choose a startup disk with Startup Manager:

1. Turn on or restart your Mac.
2. Immediately press and hold the Option key. After a few seconds, the Startup Manager appears. If you don’t see the volume you want to use, wait a few moments for Startup Manager to finish scanning connected drives.
3. Use your mouse or trackpad, or left and right arrow keys to select the volume you want to use.
4. Double-click or press the Return key to start up your Mac from the volume you selected.

If you have an optical drive connected to your computer, you can insert an installation disc to see it in Startup Manager. You can also attach FireWire or USB external hard drives that contain an operating system to add to the list of startup volumes.

Startup Manager automatically adds bootable volumes as you connect them.

Restart in OS X from Boot Camp

If you have started up your Mac in Windows using Boot Camp, you can use the Boot Camp system tray to switch your startup disk default back to OS X.

1. In Windows, click the Boot Camp icon in the system tray.
2. From the menu that appears, choose Restart in OS X.

Start from OS X Recovery

You can also start your Mac from OS X Recovery or Internet Recovery if your Mac was manufactured after 2011.

To start your Mac from the Recovery System, use these steps:

1. Start up or restart your computer.
2. Hold down the Command and R keys on your keyboard until you see the Apple logo appear onscreen.

If you don’t see a volume listed

If you don’t see the volume you want to start your computer from, check the following:

• If you’re using an external drive, make sure it’s connected and turned on.
• Make sure you’ve installed an operating system, like OS X or Windows on the drive you’re trying to start from. Volumes that don’t contain a valid operating system aren’t listed in Startup Disk or Startup Manager.
• If you’ve installed an operating system on a drive but it isn’t listed, the volume you’re trying to start from might need repair. If the volume contains OS X, start your computer from OS X Recovery and use Disk Utility to repair the volume, or reinstall OS X on the volume using the Recovery System.
• Depending on the Mac you are using and the version of OS X that is installed, the Recovery System volume (Recovery HD) might not show up in Startup Manager. Press Command-R during startup to start your Mac from the Recovery System.

For 2018 / 2019 Macbook Pro with the Secure Boot T2 Chip, see the 2018 Macbook Pro Boot from USB instructions.

By default, Mac starts from its built-in hard disk, but a startup disk can be any storage device that contains bootable contents that compatible with your Mac. For example, if you install macOS or Microsoft Windows on a USB drive, your Mac can recognize that drive as a startup disk. This guide provides 2 ways to boot a Mac from a USB flash drive.

Requirement

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

• Intel-based Mac.
• Bootable USB thumb drive formatted with a GUID partition type and containing an OS X installer or a usable operating system.

Let’s see how to boot a Mac from a bootable USB drive and what to do if your Mac doesn’t start up from it.

Way 1: Boot Mac from USB Drive using Startup Manager

Getting your Mac to load from a USB drive is fairly straightforward. Use the following steps, you can easily set Mac boot from an external drive in Startup Manager, so it’ll only boot from USB that one time.

Step 1: Insert the USB boot media into a USB slot.

Step 2: Turn on your Mac (or Restart your Mac if it’s already on).

Step 3: Press and hold the Option key immediately after you see the Apple logo. Holding that key gives you access to OS X’s Startup Manager. Once the Startup Manager screen appears, release the Option key. The utility will look for any available drives that include bootable content.

Step 4: Using either the pointer or arrow keys on the keyboard, select the USB drive you wish to boot from. Once selected, either hit the Return key or double-click your selection. The machine will start to boot from the USB drive.

Way 2: Set a Mac Boot from USB Drive using Startup Disk

When you use Startup Disk preferences to set Mac boot from an external drive, so it’ll boot from that disk until you choose a different one. Here is how:

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Step 1: Go to Apple menu > System Preference, then click Startup Disk.

Step 2: Click the locked icon and then enter your administrator password.

Step 3: Select External drive as the startup disk, then restart your Mac.

What to do if your Mac does not boot from the selected drive

If you see a message prompts that your security settings do not allow this Mac to use an external startup disk, check the External Boot setting in Startup Security Utility, and then allow your Mac to use an external startup disk.

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Step 1: Open Startup Security Utility.

Turn on your Mac, then press and hold Command (⌘) + R immediately after you see the Apple logo. Your Mac starts up from macOS Recovery. When you see the macOS utility window, choose Utilities > Startup Security Utility from the menu bar. When you’re asked to authenticate, click Enter macOS Password, then choose an administrator account and enter its password.

Step 2: Select “Allow booting from external media“.

If you want to select an external startup disk before restarting your Mac, quit Startup Security Utility, then choose Apple menu > Startup Disk.

Note: If you’re using Boot Camp in a dual-boot Windows/OS X environment, you may be unable to boot negatively into supported versions of Microsoft Windows XP, Windows Vista or Windows 10 operating systems installed on external USB hard drive.

Make sure disk has been formatted with a GUID partition type

Intel-based Macs support starting from an external USB storage device’s volume that has been formatted with a GUID partition type. If you wish to boot from the drive, it’s important to format the partition as “GUID Partition Table” rather than either of the other two ahead of time when you use that drive as a bootable drive.

Make sure your disk is bootable

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Volumes that aren’t bootable and don’t contain a copy of a valid operating system aren’t listed in Startup Disk or Startup Manager. Make sure the external drive you’re trying to start from contains a usable operating system.