Mountain Lion: Backing Up to Multiple Time Machine Drives

Time Machine is the backup system Apple built into OS X for the Mac, but has always felt a little limited — especially since it has always supported backing up your important files to only a single location. With the launch of OS X Mountain Lion, however, you can now choose multiple drives for Time Machine to use, and it’s easy to set up.

To add extra drives to your Time Machine backup routine, do this:

  • Connect the volume you want to add to your Time Machine backup schedule to your Mac. Time Machine supports hard drives and flash drives connected directly to your Mac as well as network volumes and Time Capsule.
  • Choose Apple menu > System Preferences.
  • Select the Time Machine Preference Pane.
  • Click Select Disk.

Choose the volume you want to add to your Time Machine backup routineChoose the volume you want to add to your Time Machine backup routine

  • Choose the volume you want to add to your backup routine, then click Use Disk.
  • You can choose to replace your original Time Machine backup, or to add the new volume to your routine. Click Use Both to add the new drive to your backup schedule.

Be sure to choose Use Both to add extra volumes to Time Machine's backup scheduleBe sure to choose Use Both to add extra volumes to Time Machine’s backup schedule

Time Machine will show you files from the volume it most recently used for backing up content. If you need to see files from a different backup location, just choose Time Machine > Browse Other Backup Disks.

Your Mac will rotate its backup schedule to include all of the volumes you add to Time Machine, which is great because that means you can easily have separate backups at work and home simply by keeping different hard drives at each location.

It’s also great for automatically backing up to more than one Time Machine volume at the same location. For example, you can backup to a Time Capsule on your own network, and have a second backup on a hard drive connected directly to your Mac — and you can never have too many backups of your important data.