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).
2 disks in the same machine is not a backup whether the data is copied between them using RAID or rsync or anything else.
Sounds like for this machine, just use the two disks in RAID1, or a ZFS mirror, or something. And figure out something else for backups. Probably a cloud solution.
Also, RAID2 requires a minimum of 3 disks, and is rarely used.
I’d argue it is a backup as long as something is doing snapshots of some kind to the other disk, and not realtime sync like raid. Obviously that should not be your only backup though.
3-2-1
https://www.backblaze.com/blog/the-3-2-1-backup-strategy/
It’s a ‘hot copy’ or just ‘copy’ if you rsync/whatever the files. And they’ll be gone too if the whole system fails due to power supply faulting, thunderstorm hitting the lines, misplaced coffee cup falling over, dropping the whole machine and so on…
If you make backups/snapshots they’re not the same as just a copy, still useful for recovering from accidental deletion of files or something like that. Obviously should not be your only backup though.
My most common use of the local backups for my house is someone needs a file they deleted by accident or an older version of a file.