One thing that RAID doesn't do is verify the integrity of your data on read. In other words: if you have silent data corruption somewhere you won't notice.
For many use cases that's acceptable, since it doesn't handle often, but personally I don't like it for any kind or achival/backups. That's why I picked ZFS, which stores and verifies checksums even on non-mirrored/non-raid storage. I've added RaidZ2 (similar to RAID 5 with 2 parity disks) on top of it to be able to recover from checksum errors.
bruchsturm@discuss.tchncs.de 9 months ago
If I’ve learned something about selfhosting and backups it is that you can trust HDDs to spin for 3-5 years and should still do backups. I myself do backups to HDDs that are only powered on for these backups. I’m still not sure if thats enougth.
Raid is more for an always-on solution, but not great for safe backups. They still might get damaged at the same time, because you bought them at the same time, from the same vendor and they have the same usage time.
TCB13@lemmy.world 9 months ago
Yes.
I believe it really depends on the amount of data you write to the disks. From my experience: if you’ve two disks, same model, same brand, same powered on hours they might fail at the same time and you end up with nothing thus for most people it might not even be worth to RAID at all on a home NAS. Have a main disk for always online to write / read from and a second disk that is turned on once a day to rsync all data is. Most likely safer and more reliable, you also get extra protection against accidental deletes.
rentar42@kbin.social 9 months ago
These kinds of issues are what drove me to use RaidZ2 (I went over board with using 6-disks): When during resilvering after a broken disk a second disk fails, it'll still keep the data.