Time Machine is Apple’s excellent built-in backup software for macOS. It works incredibly well, but it is also highly aggressive. By default, every single time you connect a new external hard drive, USB flash drive, or SD card to your Mac, a system prompt will immediately pop up asking, “Do you want to use this drive to back up with Time Machine?”
If you are a photographer constantly connecting different SD cards, or a video editor juggling multiple external SSDs, this incessant pop-up is incredibly annoying. It forces you to click “Don’t Use” every single time you connect a new drive. You can completely disable this automatic interrogation.
How to Stop the “Use for Time Machine” Pop-ups
You can turn off this drive discovery feature using a simple Terminal command, as Apple recently removed the graphical toggle from System Settings in newer versions of macOS.
- Open the Terminal application on your Mac (you can find it by pressing Command + Space and typing “Terminal”).
- Copy and paste the following exact command into the Terminal window:
sudo defaults write /Library/Preferences/com.apple.TimeMachine DoNotOfferNewDisksForBackup -bool true - Press Enter.
- Because this modifies a system preference, the Terminal will prompt you to enter your Mac’s administrator password. (Note: As you type your password, no characters will appear on the screen. This is normal. Just type it and press Enter).
The change takes effect immediately. The next time you plug in a brand new flash drive or external hard drive, macOS will simply mount it quietly on your desktop without launching the Time Machine setup prompt. (If you ever do want to set up a new backup drive, you can simply open Time Machine from System Settings and select the drive manually).