More recently, I looked into re-adding optical disks (this time, M-Disc at BD capacities) as one backup medium for current home servers, but the tech manufacturers just seemed even more user-hostile and Linux-hostile than they used to be. Maybe it's due to the intersection with piracy, maybe it's due to market forces of consumers who aren't very savvy about their own interests, but whatever the reason, it didn't look like an attractive option.
(Low-level burning software for optical drives was always crazy, and required some tricky alchemy by saintly open source programmers, as well as a user tolerance for burning the occasional "coaster" (failed burn). I layered my own, simpler, software atop their critical work. But I'm not interested in reinvesting in a category of media that in some ways seems to be getting worse, or even customer-hostile, at the same time that it's fallen out of popularity. If someone has better information, about how some corner of this is rock-solid, non-hostile, and otherwise viable, then I'd be happy to reconsider.)