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When you want to back up your Mac or run macOS from an external SSD, just clone your Mac internal disk (the startup disk) to the external SSD. In this article, we will show you the easiest way to clone Mac startup disk to an external SSD.

Download Mac disk cloning software

DoYourClone for Mac is one of the best Mac disk cloning applications. It offers three methods to clone data on Mac: Copy Disk, Clone OS and Create Disk Image. All of the three modes can help you back up Mac startup disk to an external SSD, but only Clone OS mode can help you create a bootable clone backup.

DoYourClone for Mac

Easy steps to clone Mac startup disk to an external SSD

DoYourClone for Mac is a 100% safe disk cloning application and it is very easy-to-use. Download and install it on your Mac, then connect the external SSD to your Mac. It is recommended to close other apps and tasks before you start OS clone.

Step 1. Open DoYourClone for Mac from Launchpad, then choose disk cloning mode - Clone OS. This mode will help you securely clone Mac startup disk to the external SSD and make it be bootable.

The startup disk (System Drive) will be selected as the source drive, you only need to click to select the external SSD as the destination drive.

Clone Mac Startup Disk to An External SSD

Step 2. Click on Clone Now button. Then it will clone all data (macOS data, Applications, files and settings included) to the external SSD.

Clone Mac Startup Disk to An External SSD

Once the process gets finished, you can use the external SSD as a backup drive, use it as a bootable drive and use it to restore macOS in macOS Recovery mode.

Clone Mac Startup Disk to An External SSD

How to set Mac startup disk?

Just connect the external SSD to your Mac, then you can set it as the startup disk. It means you can boot macOS from the external SSD backup. Follow the guide below to set startup disk on Mac.

For Intel-chip Mac:

Step 1. Just restart your Mac or press Power button to start your Mac.

Step 2. Immediately press and hold the Option (Alt) key until you see the Apple logo.

Step 3. Use the Left and Right arrow keys (or the trackpad or mouse if you can move the cursor around) to select the drive you want to boot from. Then, press Enter or select the Up icon.

Clone Mac Startup Disk to An External SSD

(If your Intel Mac uses an Apple T2 Security Chip, you won’t be able to boot from an external drive unless you modify your security settings via macOS Recovery.)

For Apple Silicon chip Mac:

Step 1. Turn off your Mac.

Step 2. Press and hold the Power button.

Step 3. Keep holding until you see Loading startup options.

Step 4. Wait for the Startup Options screen to appear.

Step 5. Use the Left and Right arrow keys (or the trackpad or mouse if you can move the cursor around) to select a drive. Then, press Enter or select Continue to boot from it.

Clone Mac Startup Disk to An External SSD

Just set the external SSD as the startup disk. Then you will boot macOS from the external hard drive, then you can continue your work or restore lost documents.

You also can enter macOS Recovery mode to restore OS using the external SSD backup.