Having got myself a new external hard drive I decided to move my MacBook Air’s Time Machine backup from the old disk (which was full) to the new one. It was at this point that I remembered that I’d done this before and, what’s more, I’d written a post about it. Anyway, that was over 18 months ago so I thought I’d try Apple’s official method again. Ha Ha. Last time Apple’s method didn’t work, maybe it’s been fixed…
Apple’s official method goes like this:
- In Disk Utility, partition your new HDD as “Mac OS Extended (Journaled)” with a GUID partition
- Open the File Info window and make sure that “Ignore ownership on this volume” at the bottom of the “Sharing & Permissions” section is not checked.
- Turn Time Machine off
- Using Finder, copy the file “Backups.backupdb” from the old disk volume to the new one.
So I did this and, after an hour or so of happy copying, it failed. More accurately, it failed on specific files which it claimed could not be copied. To be honest I wasn’t surprised, given previous experience, so this attempt was made more as an experiment than with any expectation that it would work. Thing is, why does Apple continue to push this method when it has a reputation for not working? (You can look at the Apple Discussion Forums)
Last time I copied my Time Machine files, I used Carbon Copy Cloner to do a block-by-block copy but this time, I thought, Apple’s Disk Utility could provide the solution.
First off, I used Disk Utility to perform a repair of the old backup disk, to ensure that any file corruptions or permission errors were resolved prior to copying, as this could have been a reason for the Apple method failing. I did a Partition-level repair then a File-level repair. Interestingly, neither of these found anything to repair which sort of squashed that little theory. Ah well, on to the important bit. After formatting the new volume as per Apple’s instruction (above) I was all set. Here’s the method:
- In System Preferences, turn Time Machine off
- Connect both the old and new HDDs
- Open Disk Utility
- Select the original backup disk from the list in the left column and click the “Restore” Tab.
- Drag the original backup disk volume (i.e. the one to be copied) to the “Source” field.
- Drag the new backup disk volume to the “Destination” field.
- Click the “Restore” Button.
- The copy will take some time to complete. Once it has finished, the name of the destination volume will have changed to be the same as that of the original. This could be a bit confusing so eject the original volume.
- You could change the name of the new volume but there is a risk (call that bitter experience!) that Time Machine will see this as a different disk and instead of carrying on as before, start a fresh backup and discard the backup history you were trying to retain in the first place. My preference was to simply eject the original volume before resuming Time Machine. After all, if the copy has been successful, the old one will no longer be required and after a decent period of mourning (just to be on the safe side) the old disk can be repurposed.
- Back in System Preferences, turn Time Machine on. Enter Time Machine and check that you can browse the backup history. Do a sample file restore to check everything is working as it should. If that checks out, let it perform a backup cycle, afterwards checking that the backup history can still be accessed and restored from.
And that’s it. I won’t pretend this is a quick procedure. For some people it won’t even be necessary. You’ll need to consider whether you really need to keep a long range of backups stretching back a year or more. You could always keep the original disk somewhere safe for a while and allow Time Machine to start afresh with the new disk.
Lastly, if you do try either of the above methods, you do so at your own risk. What worked for me might not work for someone else. Before you undertake any file management activities make sure you have a robust backup of any important data.