Reader Clark Ross finds his past has overgrown his present. He writes:
I use Time Machine to back up my Mac but the hard drive I use for my backups has run out of space. I plan to purchase a larger hard drive, but how do I safely move my backup from the old one to the new drive?
When you have your new hard drive in hand there’s a very good chance that you’ll need to format it. (If this isn’t a brand new drive and you have data on it, back up that data before you proceed.) To do that, tether your new drive to your Mac and launch Disk Utility (/Applications/Utilities). Select the drive and click the Partition tab. In that tab choose 1 Partition from the Partition Layout pop-up menu. Click the Options button, make sure GUID Partition Table is enabled, and click OK. The Format pop-up menu should read Mac OS Extended (Journaled). When you’ve done all that, click Apply to format the drive.
Once the drive has been formatted, move to the Finder, press Command-N to create a new Finder window, select the new drive under the Devices heading in the window’s sidebar, and press Command-I. At the bottom of the resulting Info window be sure that the Ignore Ownership On This Volume option is not enabled. Close the Info window.
Launch System Preferences, select Time Machine, and switch Time Machine off. Return to the Finder and create a couple of new Finder windows. Within the first one select your old backup drive. In the second, select the new drive. Drag the Backups.backupdb folder on the old drive to the root level of new drive to copy it.
Once the folder has been copied, return to the Time Machine preference within System Preferences, click Select Disk, select your new hard drive as the destination for your Time Machine backups, click the Use Disk button, and switch Time Machine back on.