How do I boot up my laptop from an external backup drive, or how do I verify that a backup is good?
Head over to System Preferences &lt; Time Machine and then select the "Show Time Machine in menu bar checkbox". From the menu bar, select time machine and select "Enter Time Machine". Now make sure your latest backup is visible there and you can see your files, this will ensure you have performed your backup correctly. To be safe, navigate to the disc and make sure you can see all files there.