You have your answers, but I just want to note that what I do is run rsync from cron nightly, without the delete option.

Basically this reduces the chances of losing something by accidentally deleting it on the primary drive. Every few weeks/months, I run the rsync command with the delete option to clean up.

It’s not a perfect backup by any means, especially since I could erroneously delete something right before that second rsync command and lose it for good. But it does provide a measure of safety.

Mr. Ed was a TV show in the 60s featuring a talking horse, named Mr. Ed.