A clone is a bootable backup of your Mac’s hard drive that provides redundancy for both your data and the Macintosh Operating System that you can use to boot and run your computer. If your computer’s hard drive is damaged, the bootable backup is a second copy you can use to keep working. It also makes it possible to run your own computer off other Macs, if necessary. You can also pull individual files from a bootable backup. This makes it a detailed and comprehensive backup of your computer all on one disk.
If you’d like to keep files synced between a desktop and laptop, expand your storage, or have a bootable backup copy of your system, there’s a hidden feature in Disk Utility that makes it easy to Make a Bootable Clone of Your Mac’s Hard Drive.
Use Disk Utility to Clone a Mac’s Drive
- You need a separate hard disk or partition for the clone.
- The disk should be large enough to hold all data on the source drive with at least 10GB to spare; it’s generally best to use a disk the same size (or larger) as the volume being cloned.
- The cloning process erases the destination drive, copies all files from the source drive, then makes the clone drive bootable.
- You can use an internal or external drive for the clone, with external being more common and flexible.
- Intel Macs can boot from external FireWire or USB drives, PowerPC Macs require FireWire drives.
How to Clone Mac hard drive using disk utility
Fire up Disk Utility from Spotlight (Command+Space) or the Utility folder in your applications.
You’ll be greeted with a list of all of your volumes, including your internal hard drive (probably called OS X or Macintosh HD) and your external hard drive.
Here’s where we get to that hidden feature we mentioned.
The “Restore” button in Disk Utility will copy the files from a backup to your main drive.
It’s intended to be used from Recovery mode to restore your hard drive after a failure.
But, if you choose your external drive as the restore target, you can flip that action around and copy files from your main drive to the backup.
Select your external drive in the sidebar, click “Restore” in the menu, and then select your main drive as the “Restore From” option.
You can also choose an ISO image, but that doesn’t have much use here.
Click “Restore,” and Disk Utility will start the copying process.
This can take fairly long, depending on the speed of your external drive and its connection to your Mac, so it’s best to have a fast hard drive with Thunderbolt, USB-C, or USB 3.0 connections.
And that’s it! When Disk Utility is done, you can shut down your Mac and hold down Option when booting it back up. This brings up the boot switcher and lets you boot from the external hard drive.
You can use your Mac as normal, but keep in mind that it’s separate from the installation on your main internal hard drive. Any settings you change or files you save there won’t be reflected on your primary installation.
You can do the same process in reverse if you need to copy the files back over, or restore the backup should your computer decide to break.