Swapping in a Mac for another, using a migration tool to transfer its files or upgrade a drive in Mac is very popular. However, since macOS keeps tracking Macs and drives with the hidden identifiers, the Time Machine can be confused, even when you see a prompt asking if you’d like to inherit the existing backup set for a new Mac/drive.
If there is something wrong with your MacOS, you will need to turn to the Terminal command line and enter the required text commands to bring things back on track.
Before getting started, we recommend that you are making some changes to your Time Machine backups! If something goes wrong, you could lose all your entire backup history, because Time Machine is finicky.
If you don’t get used with the following instructions to type commands in the Terminal, you should seek out help, it can easily get things wrong due to the precise syntax specifying the drive names and paths.
There are currently two different types of Time Machine reconnections, which are inheritance and volume association.
The first Inheritance helps in connecting to a different backup for the whole computer, which is often called a “machine directory.” These sets can be found in Backups.backupdb as the name of the computer. But each computer comes with a unique folder. When transferring from one Mac to another and connecting the currently existing Time Machine backup, you inherit it & transfer the identity in the Time Machine backup to the new Mac.
While the second one, Volume association, relates to the disk volume within a set. These can be found in “snapshot volumes,” and search for something like this in the path:
Backups.backupdb/Glenn’s Mac/2018-03-03-123456/ Mac Drive
There are many cases that you use association to resolve a Time Machine backup set since the association is built on a different identifier for each drive. You will have to re-associate when you:
- Delete a drive and then restore its data.
- Swap a drive in Mac and then restore the contents.
- Upgrade to a new Mac and transfer the data on your old Mac to it.
You can drag and drop a folder from the Finder into the Terminal, which might be the best way to make sure the patch is correct compared to typing it by hand. Dragging also represents other special characters read correctly in the Terminal.
Also read: How To Fix 5 Common MacBook Problems
Also remember to provide the administrative privileges with the current account on the Mac. Follow the below steps if you want to inherit a machine directory when switching Macs:
- Paste sudo tmutil inheritbackup into the Terminal
- Press the Space button
- Next, drag and drop in your Time Machine machine directory. If it’s a networked volume, drag the sparsebundle file, you don’t double click on it which will mount it.
- Click on Return.
- When prompted, enter your password.
- The inheritance is now done.
For each volume, you should change the associations if you’re just swapping volumes. You are connecting to a current volume with a volume nested in a snapshot within a machine directory. Simply do these following steps:
- Paste sudo tmutil associatedisk -x
(The -x means to update the identical volumes, so you should only do this once.)
- Press the Space
- Drag the new Mac volume that you want to associate with the old volume’s backup into Terminal.
- Enter Space key.
- Go to the Backups.backupdb folder to the computer name; note the Latest snapshot and the drive name for associating. Drag that drive into the Terminal after pressing Space button. If it’s a networked volume, double-click on the disk image to open it and double click on Latest to access the volumes.
- Next, press Return.
- When prompted, type in your password.
Time Machine will now sync the volumes and just back up files changed if everything goes well.