If you got overwhelmed in trying to understand how to do it, just do it the easy way: create a ZFS pool of two drives of identical size in mirroring. Then, make sure to have regular scrubs (this means ZFS will regularly check all files for corruption, and recover from eventual errors), use your OS' task scheduler (e.g. Systemd or cron) to run this once a month. This should be sufficient to protect you from bit rot.