OS X Mountain Lion is the second version of the Mac OS that Apple will sell primarily through the Mac App Store. Apple's first adventure with direct digital download sales of its Mac operating system was OS X Lion, which actually went very well.
The one area where many Mac users have had a bit of a problem with downloading OSes from the Mac App Store is the lack of a physical installer, primarily a bootable DVD or USB flash drive. OS X Mountain Lion continues this trend by deleting the bootable installer as part of the Mountain Lion setup process.
You can always re-download the OS if you need to, or have the OS X Recovery HD that is created as part of the installation do a re-install for you, but for many of us, having the OS X installer on portable media (DVD or flash drive) is a must.
If you would like to create a bootable OS X Mountain Lion DVD or USB flash drive, this guide will walk you through the process.
What You Need
A dual-layer DVD. This type of DVD has two layers, which increases the available recording space to roughly 8.5 GB. The OS X Mountain Lion installer is just a smidgen too big to fit on a standard DVD. Dual-layer DVDs, also called DVD9, are available just about anywhere standard DVDs are sold.
You can also use a USB flash drive that can hold 5 GB or more (8 GB and 16 GB are commonly available sizes) as your bootable media.
- A valid copy of OS X Mountain Lion, which you must purchase and download from the Mac App Store. It will be stored in the Applications folder on your Mac; the file is called Install OS X Mountain Lion. Please note that you must create the bootable copy of the installer before you actually perform the Mountain Lion installation, because the Mountain Lion setup process deletes the files you need to make the bootable installer copy.
If you have already installed Mountain Lion, but you want to create the bootable installer we describe here, you will need to follow this guide to re-download Mountain Lion from the Mac App Store.