Sometimes it’s helpful to create a bootable clone of your Mac, such as for testing software or implementing system changes. For example, I often do this to test in-beta versions of macOS.
What is macOS cloning?
When you clone your Mac’s hard drive you create a bit-by-bit, duplicate of it. This includes the data allowing you to boot your system right from that copy. In another word, a cloned hard drive is an exact copy of the original, including the operating system and all the files it needs to boot up and run.
This is great for moving data from one Mac to another. But cloning is also handy for backing up your data.
However, the cloning process has become more difficult because of the “signed system volume” in macOS Big Sur and later, including macOS Ventura.
So what’s a signed system volume? Here’s Apple’s explanation:
macOS includes enhanced protection for your Mac with cryptographic technology (macOS 11 or later) that prevents access to or execution of files that don’t have a valid cryptographic signature from Apple. All system files are protected on the signed system volume (SSV). This advanced system volume technology provides a high level of security against malicious software and tampering with the operating system.
It also allows software updates to complete in the background while you work, which reduces the time it takes for your Mac to restart and complete updates.
How to clone your Mac
Preparing your external hard drive
However, you go about cloning your Mac, you need to make sure you have an external disk with plenty of space. You can use a drive with just about any sort of connectivity. However, I recommend a USB 3.0 drive, as it strikes a nice balance between speed and price.
You’ll need to format the external hard drive before cloning. Here’s how:
- Connect your external drive to your Mac.
- Launch the Disk Utility app.
- Find the hard drive under External and select it.
- Click the Erase tab at the top of the window.
- Name the drive and select macOS Extended (Journaled) from the format list.
- Click Erase.
- Click Done once the process is finished.
- Close Disk Utility.
Your external drive is now properly formatted for cloning your Mac and you can proceed with cloning inside your third party app of choice. For instance, for creating a Mac clone inside Carbon Copy Cloner you would:
- Open the app
- Choose the volume that you want to clone from the Source selector.
- Choose your now properly-formatted volume from the Destination menu.
- Click the Clone button.
Cloning a Mac with Disk Utility
Instead of a third party app, you can also clone your Mac with Disk Utility. Here’s how:
° Launch Disk Utility.
° Choose the backup drive you want to use.
° Click Restore.
Disk Utility will display a new window with a drop-down menu dubbed Restore from. Select your Mac SSD from the drop-down menu as the source drive. Click Restore to begin the cloning process.
Then, Disk Utility will show you a status bar as the cloning process take place. When it’s done, click Done (d-uh) Done.
Using your clone
If you’ve made a complete, bootable clone (the default option in most cloning apps) then all you have to do is connect your external drive with the clone on it to the Mac you want to copy it to.
In macOS Ventura, go to System Settings > General > Startup Disk.
Choose the external drive as your startup disk, then click Restart. Then use the cloning app to copy your clone to the destination disk or SSD.
You can also make a disk image rather than a bootable clone. Disk imaging is the process that compresses the hard drive data, including the operating system, in the form of an image. It also has the information required to boot the operating system.
To do so, connect your external drive but don’t change the startup disk. Launch Migration Assistant and choose the option to restore from your disk image.