How to Migrate a Time Machine Backup to Another Drive

Maybe your Time Machine drive is full. Maybe you’re worried about an older hard drive dying on you, taking your backups with it. Whatever the reason, you want to migrate your Time Machine files from one hard drive to the other.

Good news: it’s relatively straightforward. All you really need to do is format your new drive correctly, drag over the files, and set your new drive up to be the backup destination. There are a few details to think about along the way, however, so let’s go over everything step-by-step.

Step One: Turn Off Time Machine

Before you do anything head to System Preferences > Time Machine on your Mac and uncheck “Back Up Automatically.”

The reason is simple: you don’t want a new backup starting while you’re migrating your files. It will slow you down and potentially introduce conflicts.

Done? Good, let’s keep going.

Step Two: Connect and Format Your New Drive

Go ahead and plug in your new hard drive. It’s likely not formatted properly, so we need to use Disk Utility to get things just right. Open Disk Utility with Spotlight, or by heading to Applications > Utilities > Disk Utility in the Finder.

Click your new hard drive in the left panel, then click “Erase.” Make sure you’re not erasing your old Time Machine drive before doing anything.

Write the drive as “MacOS Extended (Journaled)” using the “GUID Partition Table”.

A few things to keep in mind:

Click “Erase” when you’re ready and the drive will be reformatted.

Step Three: Copy Your Files

Now we can copy our files over from the old Time Machine backup to our new one. Head to the old drive and you’ll see a folder called “backups.backupd.”

Drag this entire folder over to your new drive. The process will most likely take a few hours, so plug your laptop into the outlet and consider keeping your Mac awake to make sure this gets done.

Note that things work a little differently for Time Machine backups over a local network because of how network drives store things. There are sparsebundle files, one for every Mac that backs up to the destination, each with a “backups.backupd” folder inside them. If you’re migrating from one network backup to another, simply drag the bundle(s) over from source to destination. If you’re migrating from a network backup to a local drive, open the sparsebundle file; you’ll find the “backups.backupd” folder inside, and you’ll want to copy that over to your new external drive. Local drives can only back up a single Mac.

Step Four: Switch Time Machine Drives

When the transfer is complete head to System Preferences > Time Machine once again, then click “Select Disk.”

You will see both your old and new drives. Click the new drive, then click “Use Disk.”

You’ll be asked if you want to switch or use both drives:

Click “Replace” unless you have some reason to keep two backups running.

Ensure that “Back Up Automatically” is checked and you should be good to go. A new backup will run on the new drive.

Your old Time Machine backups can be found alongside all of your new ones. Enjoy!

Photo credit: Tanyapatch/Shutterstock.com

Justin Pot is a staff writer for How-To Geek, and a technology enthusiast who lives in Hillsboro, Oregon. Follow him on Twitter and Facebook, if you want. You don't have to.