Mountain Lion makes it easier to create multiple Time Machines backups. Chris Breen explains how.
You explained that you needed to manually choose the different volumes you’d use for backup. I too want multiple backups of my Mac’s data and was hoping the process was easier now.
If your Mac is running Mountain Lion, it is easier. It goes like this.
Designate another volume as a second backup destination—a hard drive attached to your Mac or a network volume, for example. Launch System Preferences and then select Time Machine. Click the Select Disk button and you should see not only the volume you’re currently using for your backup but also any volumes available to you (that second destination you just added being one of them).
Select that volume and click Use Disk and a sheet will appear asking if you’d like to replace your original backup destination or use both volumes. Click on Use Both. Time Machine will then set about creating a backup archive on the second volume and then back up your Mac to it.
Via David Anders