While Time Machine is a great way to backup your Mac, sometimes it can be very useful to create a disk image of your Mac OS X hard drive to store on an external drive. One example would be if you were intending to replace your MacBook’s hard drive.

Creating a backup disk image with Disk Utility allows you to take an exact snapshot of your present hard drive, and then restore it to the new drive once it is fitted.

In this tutorial we’ll take you through the necessary steps to create a backup of your Mac with Disk Utility:

1.) First, ensure you have a external USB 2.0 or Firewire hard drive connected to your Mac, and make sure it has enough spare disk space to store an image of your present hard drive:

Attaching External Drive to Backup Mac to.png

2.) Go to Applications, then Utilities and double-click on Disk Utility. The application will open, presenting you with this interface:

Disk Utility Interface OS X.png

3.) Close any other open applications, and then select your Mac’s internal hard drive from the left-hand pane of Disk Utility:

Selecting Mac Hard Drive to Backup in Disk Utility.png

4.) Click on File in the toolbar, then select New then Disk Image from [your hard drive]:

Selecting Disk Image from Mac Hard Drive in Disk Utility.png

5.) Name your Mac backup and then select your external drive as the destination in the Where drop-down menu:

Selecting Destination of Backup in Disk Utility.png

6.) You can opt to change the Image Format settings:

Image Format Settings in Disk Utility.png

or the Encryption settings:

Selecting Encryption Settings for Backup in Disk Utility.png

But for general use we would recommend leaving them as the defaults of “compressed” image format and no encryption.

7.) Click Save to begin the process of creating the disk image on your external hard drive. Disk Utility may require some considerable time to create the backup of your Mac depending on how much stored data your internal drive holds.

Disk Utility will notify you when the process is finished. You will now have a complete copy of your Mac’s hard drive from which you can restore in the event of an emergency reformat or hard drive replacement.