Mac: You can easily download Mac 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, after you run the installer on your system, it disappears from your Applications folder. You can restore 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. However, to save time, it's best to do this disc burning before you update your Mac to Mountain Lion.
The Easy Option: Use Lion DiskMaker
Lion Disk Maker is a donationware app from Serial Server. Version 2rc2 burns Mountain Lion or Lion to an external drive or DVD. You'll need at least an 8GB USB flash drive, USB/Firewire drive or SD card to make the bootable disk or a single-layer or dual-layer writable DVD. Note that the program will overwrite all files on your USB drive or SD card when creating the bootable disk.
Lion Disk Maker finds your copy of Lion downloaded to your Applications folder, asks you what media type you want to use to create the install disk, then handles the rest.
DIY Option: Use OS X's Built-in Disk Utility
The steps for burning Mountain Lion to disk are essentially the same as the ones used for Lion:
- Download Lion from the Mac App Store — but don't install it yet (because of the disappearing installer issue noted above).
- 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"
- Open up Disk Utility from your Applications > Utilities folder and drag the DMG file into the sidebar on the left.
- If you're burning to DVD: insert your disc, select the DMG file in the sidebar, and click on "Burn". Skip to step 6.
- 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 the drive (this will completely erase it).
- 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 complete the process.
- 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 a number of handy utilities on it, including Disk Utility and Time Machine recovery.
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.