If a Time Machine backup takes longer than you expect

Your first backup may take a long time, depending on the number of files to back up.

How to get the best Time Machine performance

After the first Time Machine backup, future backups should be faster because Time Machine only backs up the changes that have occurred since your last backup. If most backups take longer than you expect, try these solutions.

Upgrade to macOS Big Sur

macOS Big Sur significantly improves Time Machine performance when used with an APFS-formatted backup disk. You will automatically get this benefit after creating a new backup disk in Big Sur.

If you're backing up to the same disk that you were using before upgrading to Big Sur, follow these steps:

  1. Select your backup disk in the Finder.
  2. Choose File > Get Info from the menu bar, then look for the information labelled Format. 
  3. If the format isn't APFS, but you want improved Time Machine performance in Big Sur, use Disk Utility to erase the backup disk. This permanently deletes any backups and other data on that disk. 
  4. Set up Time Machine to use the backup disk again. After the first backup has been completed, future backups should be faster.

Check for large, frequently updated files

Some apps store data in unusually large, frequently updated files. Backing up such files can be time consuming. Try these solutions:

  • Upgrade to macOS Big Sur and an APFS-formatted backup disk, as described above.
  • Or contact the app developer to find out how to best use their app with Time Machine. 
  • Or exclude those large files from your backup: open Time Machine preferences, click Options, then click the add (+) button to add a file or folder to be excluded.

The Reduce Clutter feature of your Mac can help you identify large files and shows when they were last accessed.

Check for apps that keep your backup disk busy

Only use your Time Machine backup disk for Time Machine. Some apps, such as antivirus utilities, may keep your backup disk busy by frequently accessing the disk to find or save items. Find out whether the app's settings can be changed to prevent that from happening.

Check your network performance

If you're using your Time Machine backup disk over a network, backup speed is affected by the performance of your network. If you're experiencing poor Wi-Fi performance, analysing your wireless environment may help you identify issues. You may get better performance by connecting the backup disk directly to your Mac.

Check your backup disk for issues

Time Machine should tell you when it can't complete a backup because of a problem with your backup disk, but you can use Disk Utility to check your disk for issues at any time. 

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