I have a MacBook Air, am currently running Catalina, and using Time Machine with a WD My Passport for Mac drive. I have been blissfully running Time Machine and the WD drive for around five years. So far (as far as I know) everything is working great. But is it? I honestly have no idea! How do I know if my WD drive is working? Will some warning sign pop up on the screen if it isn't? What kind of check should I do to find out if all is well?