Many of you may have noticed that you can’t use cp or ditto to move Time Machine backups. But you can use asr. This is because moving a Time Machine backup needs to be block level in most cases. Let’s look at doing so in Disk Utility.
Disable Time Machine
Moving Time Machine backups to a new disk is a bit tricky for some, due to the restrictions placed around the files that Time Machine uses. To do so, first disable Time Machine. To do so, open the Time Machine sytem preference pane turn off Time Machine.
Partition the New Volume
Next, connect the current backup volume and your new volume (which can be a disk image). Then open Disk Utility from /Applications/Utilities. From the left sidebar of Disk Utility, click on the new volume that you wish to use for Time Machine. Then click on the Partition tab and then at the Volume Scheme pop-up, click on 1 Partition. Click on Options and make sure GUID Partition Table is selected. Then click on OK and provide a name for the new backup volume. The Format pop-up menu should read Mac OS Extended (Journaled). If so, go ahead and click on the Apply button.
Restore the Old Volume to the New Volume
Next, click on the Restore tab and drag the icon for the existing Time Machine volume from the Disk Utility sidebar to the Disk Utility Source. Then drag the new volume from the Disk Utility sidebar to Destination. This is important: Check the Erase Destination checkbox! Then click on Restore twice and wait for the copy to finish (it can take awhile).
Enable Time Machine Again
Now we want to turn Time Machine back on, selecting our new target volume. Open System Preferences and click on Time Machine. Then use the Select Disk button to choose the new volume. Close System Preferences and you should be back in business.
