Such pedantic toxic tone here people. Let’s analyse.
Premise:
- RAID 1 to protect from disk failure and RAID 0 for performance (oversimplified, sorry.)
- Other than HDD, many components along the pipeline of storage can fail. So, RAID 1 is solving only against disk failure. You should check everything in system should be replaceable to a reasonable degree.
- Backup to another complete separate system is literally the best since it has all the ingredients of RAID + easy duplication of hardware too (also eliminating need to find exact duplicate hardware.)
- the only reason why RPI4 should not be considered is because it’s not “purpose built” for storage and has more things between your data and you that can go wrong. Having said that many commercial NASes are SBCs with onboard SATA and specially tuned OS as the only difference between Pi 4)
- everything can go corrupt or fail in various degrees of MTBF. Hence the only way to have peace of mind is reduce the number of things that can fail and use only high MTBF stuff
Practical:
- it may not be feasible to have two systems (for whatever reason)
- the joy of diy creating NAS is priceless
- if creating worthwhile NAS needs a PhD, that defeats whole purpose of OMV and this community.
- at times, there’s just another spare disk than a spare SBC and hence many want to use it than waste it.
- setting up differential backup has been historically tricky unless you’re using TimeMachine or some other proprietary software and as such has a bad rap among many. (Cue for OSS developers here to make their work more accessible for the masses.)
- the backup method is also not that “cohesive”. If your backup fails / or main NAS fails, re-setting up backup is not like swapping drives but repeat of same multi step setup of the syncing software.
All things said, I have a NAS that I use for actual backup and that has RAID. I went commercial WD NAS so that I can avail their service. This is where I store very very priceless data. On the other hand I have one RPI4 with one USB HDD and OMV that also syncs (backup) to my WD NAS.
Best of both worlds.