I am mainly hosting Jellyfin, Nextcloud, and Audiobookself. The files for these services are currently stored on a 2TB HDD and I don’t want to lose them in case of a drive failure. I bought two 12TB HDDs because 2TB got tight and I thought I could add redundancy to my system, to prevent data loss due to a drive failure. I thought I would go with a RAID 2 (or another form of RAID?), but everyone on the internet says that RAID is not a backup. I am not sure if I need a backup. I just want to avoid losing my files when the disk fails.
How should I proceed? Should I use RAID2, or rsync the files every, let’s say, week? I don’t want to have another machine, so I would hook up the rsync target drive to the same machine as the rsync host drive! Rsyncing the files seems to be very cumbersome (also when using a cron job).
So the minimum I would do is set up a backup to the drive using Restic or something similar. Make sure it runs at least daily, and keep snapshots for a month or more.
Make sure the backup drive can only be accessed by the Restic user account, and not any of the other service accounts to minimize chances of a misconfiguration or something damaging the backup data.
Obviously this will not protect against physical damage like a lightning strike or major power surge, or malware or config errors big enough to wipe out the whole system and all the drives attached to it.
So for any more important data that isn’t replaceable, it needs to be backed up online as well to a service like Backblaze B2 using Restic.