I can highly recommend BTRFS RAID multi-volume modes. I couldn't figure out how to get the bootloader to enable searching for the volumes but my data is on a raid stripe with duplicated metadata, and the backup of that data on a jbod with duplicated metadata, replicating with lsyncd.

Degoogling and generally being a custodian of your own data is a very important thing. Those big corporations are centralised and thus prone to sudden dramatic failures.