So if you plan to use that installer on other Macs, or-in this case-to create a bootable drive, be sure to copy the installer to another drive, or at least move it out of the Applications folder, before you install. Our main Mountain Lion-installation article, if you leave the Mountain Lion installer in its default location in the Applications folder when you install OS X 10.8, the installer will be deleted automatically after the installation finishes. Our article on making a bootable Lion-install drive. Using Disk Utility,” below, but from Step 6 on, follow the instructions under “To create a bootable DVD” in That said, if, for whatever reason, you absolutely need to create a bootable install DVD, follow steps 1 through 5 under “ In addition, you can easily update a USB stick or external hard drive each time an update to Mac OS X is released, as explained below with a DVD, you have to toss the disc in the trash and start over, which is both a hassle and bad for the environment. More and more Macs ship without a built-in optical drive booting and installing from a DVD is very slow and 8GB flash drives can be found for $10 or less-there’s little reason to opt for a DVD anymore. Though it’s possible to make one, I don’t recommend it these days. Select Recovery HD from the Startup Manager.You may have noticed that I didn’t mention making a bootable install DVD. To access OS X Recovery, reboot the computer while holding the Option key. When the OS X Recovery Disk Assistant completes, the new partition will not be visible in the Finder or Disk Utility.

Insert an external drive, launch the OS X Recovery Disk Assistant, select the drive where you would like to install, and follow the on-screen instructions. To create an external OS X Recovery, download the OS X Recovery Disk Assistant application. Note: In order to create an external OS X Recovery using the OS X Recovery Assistant, the Mac must have an existing Recovery HD.

The OS X Recovery Disk Assistant lets you create OS X Recovery on an external drive that has all of the same capabilities as the built-in OS X Recovery: reinstall Lion or Mountain Lion, repair the disk using Disk Utility, restore from a Time Machine backup, or browse the web with Safari. Built right into OS X, OS X Recovery lets you repair disks or reinstall OS X without the need for a physical disc.

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