How to Move Time Machine to a New Backup Drive

Transferring a Time Machine backup to a new drive was never easier

iMac with Time Machine logo
Apple Inc.

It's a law of the universe. Sooner or later, Time Machine backups expand to fill all available space on a hard drive. That's OK because by using all available space, Time Machine can keep backups of work going back as far as … well, as far as there's available space.

Eventually, you may decide you need more room for your Time Machine backups and want to move them to a larger drive. You may need more room for two reasons. The amount of data you store on your Mac has no doubt grown over time as you added more applications and created and saved more documents. At some point, you may outgrow the amount of space available on your original Time Machine hard drive.

The other reason for needing more room is a desire to store more data history. The more data history you store, the farther back in time you can retrieve a file. Time Machine obligingly saves multiple generations of documents or other data, as long as you have enough room to accommodate them. However, when the drive fills up, Time Machine purges older backups to provide room for the most current data.

Selecting a New Time Machine Drive

The requirements for a Time Machine drive are not complex, with just about any standard hard drive or SSD making the grade. The speed of the drive is not a primary consideration. With a Time Machine, drive size is more important than overall performance.

External enclosures are an excellent choice for Time Machine drives, allowing you to connect the drive to your Mac using Thunderbolt or USB 3 depending on your needs. USB 3 and later enclosures are by far the most popular and the least expensive of the enclosure options, and they are a good value for this use. Just make sure the enclosure is from a reputable manufacturer.

Moving Time Machine to a New Drive

Starting with Snow Leopard (OS X 10.6.x), Apple simplified the requirements to transfer a Time Machine backup successfully. Follow these steps to move your current Time Machine backup to a new, larger drive. Time Machine then has enough space to save a larger number of backups until it eventually fills up the available space on the new drive.

Preparing a New Hard Drive for Time Machine Use

  1. Connect the new hard drive to your Mac, either internally or externally. External drives can connect to a USB, Thunderbolt, or FireWire port on the Mac.

  2. Start up the Mac.

  3. Time Machine works with drives that are formatted in Mac OS Extended (Journaled) formats and Xsan formats. If the backup drive you attach isn't formatted in one of the Mac's acceptable formats, you are prompted to erase it. With some OS versions, the Mac prompts you to reformat at this step. If not, you can format the drive using Disk Utility.

    Formatting the hard drive erases any data on the drive.

  4. To format the new hard drive using Disk Utility, follow the instructions in one of the guides below and then return to this guide:

  5. Once you finish formatting the new hard drive, it mounts on your Mac's desktop.

  6. Right-click the new hard drive icon on the desktop, and select Get Info from the pop-up menu.

  7. Make sure that Ignore ownership on this volume isn't checked. If you need to change it, click the padlock icon located in the bottom right corner of the Get Info window.

  8. When prompted, supply an administrator's username and password. You can now make the changes.

Transferring Your Time Machine Backup to a New Hard Drive

  1. Launch System Preferences by clicking the System Preferences icon in the Dock, or selecting System Preferences from the Apple menu.

  2. Time Machine preferences screen
    Time Machine preferences.
  3. Slide the Time Machine switch to Off or remove the check mark from the Back Up Automatically box. Both perform the same function. The interface was changed on later versions of the Time Machine preference pane.

  4. Return to the Finder and browse to the location of the current Time Machine backup.

  5. Click and drag the Backups.backupdb folder to the new drive. The Backups.backupdb folder is usually found in the top-level (root) directory of the current Time Machine drive.

  6. If asked, supply an administrator name and password. The copying process starts. This can take a while, depending on the size of your current Time Machine backup.

Selecting the New Drive for Time Machine's Use

  1. Once the copying is complete, return to the Time Machine preference pane and click Select Disk.

  2. Select the new disk from the list and click Use for Backup.

  3. Set the Time Machine switch to On or check the box in front of Back Up Automatically.

That's all there is to it. You're ready to continue using Time Machine on your new, spacious hard drive, and you didn't lose any of the Time Machine data from the old drive.