[mschmitt]

I've been using the scheduled backup feature, with the target drive unmounted before the copy. I've noticed that at the end it unmounts the system volume, which removes the icon from my desktop, but more often than not it fails to unmount the data volume. I only notice this days later.

I'm guessing it is because of Spotlight dissenting* from the unmount. What I'm wondering is if SuperDuper! could try again later, until it is unmounted. I'm thinking it would only do that if it was just the Data volume mounted, so you don't unmount a volume that the user mounted.

* which is annoying. If I tell macOS to eject a drive, it should do it! Background tasks like Spotlight that aren't required to complete should let go.