Make a backup
Back up your Mac, especially if you plan to install a beta version of macOS. Beta software is software that is still in development, so some apps and services might not work as expected.
Add an APFS volume
- Make sure that your Mac is using macOS High Sierra or later.
- Open Disk Utility, which is in the Utilities folder of your Applications folder.
- In the sidebar, select your existing APFS volume, such as Macintosh HD.
- Choose Edit > Add APFS Volume from the menu bar, or click the add volume button (+) in the Disk Utility toolbar. These options are available only when an APFS-formatted volume is selected.
- Type any name for the new volume, then click Add.
- Quit Disk Utility.
Install a compatible macOS on the new volume
If the macOS that you want to install is compatible with your Mac, you can install it on the new volume.
- To install the latest beta (prerelease) version of macOS, enroll your Mac in the Apple Beta Software Program and follow the installation instructions on the program website.
- To install the latest release version of macOS, download it from the App Store.
- To install a version earlier than the version currently installed, use a bootable installer of macOS High Sierra or later.
When the installer opens and you're asked to choose where to install, click Show All Disks, then select the new volume before continuing.
Switch between macOS versions
To switch between installed macOS versions, just start up your Mac from the other volume. You can do that by changing your Mac startup disk.
When you first start up from a new volume, a setup assistant helps you to create a new user account. User accounts are not shared between volumes, but you can share files between user accounts.
Keep macOS up to date on each volume
To get the latest updates for each version of macOS, check for software updates, then start up from the other volume and check for software updates again.
Delete a volume
If you want to delete a volume, including the macOS and all other data on that volume, follow these steps.
- Start up your Mac from a volume that you are not deleting.
- Open Disk Utility.
- From the sidebar in Disk Utility, select the volume that you want to delete.
- Choose Edit > Delete APFS Volume from the menu bar, or click the delete volume button (–) in the Disk Utility toolbar.
- Click Delete. If the volume is part of a volume group, delete the volume group when prompted.