Using Time Machine with an external storage device

Overview

If Microsoft OneDrive does not meet your computer backup needs, you can use Time Machine to automatically back up your Mac files and folders to an encrypted external storage device.

Be aware that:

Time Machine will erase any existing files or folders on the storage device
The storage device can only be opened by Macs, not Windows computers
The storage device must be connected to your computer in order for backups to take place

Before you begin, make sure that you already encrypted the device.
Connect the external storage device to the Mac, and unlock the device with your password.
Open the Apple menu (upper left in the menu bar) and select System Settings.
In the left menu, select General. Then, select Time Machine.
Click Add Backup Disk.
Select the device, and click Set Up Disk.
Next to Encrypt backup, click the toggle to deselect it. Then, click Done.
If prompted, click Erase to confirm.
Time Machine begins the backup, and by default will back up your entire computer.
(Optional) To customize the backup frequency and the folders to be backed up, click Options:
- To change the backup frequency: Use the Backup Frequency field. You can back up your computer automatically on an hourly, daily, or weekly basis, or back it up manually. Be aware that the external storage device must be connected to the Mac for all of these options.
- To exclude folders from the backup (for instance, you may want to exclude your OneDrive or Google Drive folder, as they are already backed up to the cloud):
  1. Click the + icon.
  2. Select the folder you want to exclude, and click Exclude.
  3. Repeat steps 1–2 until you are done excluding folders.
  4. Click Done.

Before you begin, make sure that you already encrypted the device.
Connect the external storage device to the Mac, and unlock the device with your password.
Open the Apple menu (upper left in the menu bar) and select System Settings.
In the left menu, select General. Then, select Time Machine.
Click Add Backup Disk.
Select the device, and click Set Up Disk.
Next to Encrypt backup, click the toggle to deselect it. Then, click Done.
If prompted, click Erase to confirm.
Time Machine begins the backup, and by default will back up your entire computer.
(Optional) To customize the backup frequency and the folders to be backed up, click Options:
- To change the backup frequency: Use the Backup Frequency field. You can back up your computer automatically on an hourly, daily, or weekly basis, or back it up manually. Be aware that the external storage device must be connected to the Mac for all of these options.
- To exclude folders from the backup (for instance, you may want to exclude your OneDrive or Google Drive folder, as they are already backed up to the cloud):
  1. Click the + icon.
  2. Select the folder you want to exclude, and click Exclude.
  3. Repeat steps 1–2 until you are done excluding folders.
  4. Click Done.