Once again considering usage of optical media (#DVD or #BD, likely #MDisc) for personal #backups. Usually I encrypt all the backups, using LUKS or ZFS's encryption, but unsure about those on optical media: does it work with Linux to prepare a LUKS image, with UDF on top, and burn that onto a disk? Or is it easier to prepare an encrypted file, to be mounted as a loop device on reading, and write it on top of UDF? I also wonder how well-supported such external drives are by Linux, whether it is on the painful side of compatibility.
Also trying to choose between DVD and BD. I see very few external BD drives in local stores (possibly because those are also harder to power, requiring two USB cables) and those are more expensive, but apparently the Blu-ray disks themselves are supposed to last longer, it must be more convenient to use larger-capacity disks, and the M-DISC ones I see in local stores are all BD.
As a side note, I discovered that while it is hard to find computer cases with proper HDD bays these days, those show up in online stores' listings once you add a filter condition for external 5.25-inch bays. As a bonus, apparently those tend to not be covered in LEDs.