Leopard: Changing Time Machine Disks

The first time you connect an external hard drive your Mac after installing Mac OS X 10.5, you have the option to use that drive to back up files with Time Machine. If you decline, but later change your mind, or you accept and later want to use a different disk, Leopard makes it easy to select a new Time Machine target disk.

Make sure the hard drive you want to use for your Time Machine backup is connected to your Mac.
Choose Apple menu > System Preferences to launch System Preferences.
Click the Choose Backup Disk button.

Select a new backup disk from the Time Machine Preference Pane.

Select the drive you want to use, and then click the Use for Backup button.

Choose your new Time Machine disk, and click the Backup button.

If you change your Time Machine target disk, donit worry about losing the files that were already backed up on your original target disk. Time Machine will leave those alone, so you can still go back and look through the documents any time you want.