OS X Mountain Lion Bible

Working with Disks and Backups

The ability to encrypt disks through the contextual menu in the Finder (right-click or Control+click a disk to get it) is new to OS X Mountain Lion.

OS X Mountain Lion lets you use multiple disks for your backup, an approach that can add extra security in case one backup disk fails. After selecting one backup disk, click Select Disk in the Time Machine system preference, select a different disk, and click Use Backup Disk. A settings sheet appears asking if you intend to use multiple disks for backup or if you want to change the backup disk. Click the appropriate option—Add Backup Disk or Change Backup Disk, respectively. You also can click Choose a Different Disk and then either choose a different disk for use as your backup or additional backup (if you picked the wrong one) or click Cancel to neither add another backup disk nor change the current one.

If you have a 2012 or later Mac model, OS X Mountain Lion's Power Nap feature lets it back up via Time Machine while the Mac is asleep—if the backup disk is turned on, of course.