How to Burn OS X Mountain Lion to Disk Using the Built-in Disk Utility

You can easily download OS X Mountain Lion from the App Store any time after purchasing it, but if you want your own physical copy of the installation, here’s how to make your own Mountain Lion install DVD or USB drive.

Having the installer on physical media is necessary if you ever want to do a clean install of the operating system or install it on a Hackintosh.

As with last year’s Lion upgrade, once you run the installer on your system, it disappears from your Applications folder. You can get it back by holding down the option key while clicking on the purchases tab to re-download the file or restore the installer from a Time Machine backup, but to save you some time, it’s best to do this disc burning before you update your Mac to Mountain Lion.

The steps for burning Mountain Lion to disk are essentially the same as the ones for Lion:

  1. Download Lion from the Mac App Store—but don’t install it yet, because of the disappearing installer issue.
  2. Find the installer in your Applications folder and right-click on it then select “Show Package Contents.” Head to Contents > SharedSupport and look for the file called “InstallESD.dmg”
  3. Open up Disk Utility from your Applications > Utilities folder and drag the DMG file into the sidebar on the left.
  4. If you’re burning to DVD: insert your disk, select the DMG file in the sidebar, and hit “Burn.” Skip to step 6.
  5. If you’re burning to USB, you’ll need to first format the drive properly:
    • Insert the disk and select it in the sidebar in Disk Utility. Select the Partition tab, select “1 Partition” from the dropdown menu and choose “Mac OS Extended (Journaled)” for the format type.
    • Click the Options button and choose “GUID Partition Table”—this will make the drive bootable and formatted correctly for the Mac. Hit Apply to format—which will completely erase—the drive.
    • Now click the Restore tab and choose the DMG file as your source and the USB drive as the destination. Hit the Apply button to make it happen.
  6. Finally, to boot from your install disk/drive and install Mountain Lion, restart your Mac and hold the Option key down when you hear the startup chime.

Besides installing Mountain Lion, your installer disk/drive will have the host of handy utilities on it such as Disk Utility and Time Machine recovery.

Note that when you install Mountain Lion, you’ll have a recovery partition on your drive in case something goes wrong. That said, it’s always nice to have a disc or flash drive handy in the event you need to perform a clean install.