I use raid5 on an HP server, and am dealing with 2 drive failures, because HP’s qc is garbage. Raid6 would have saved me here, but it’s not really likely to have 2 drives fail simultaneously, so… yeah.
I recommend looking into 321 backup, too. Raid isn’t a backup solution, but it seems you already understand that and are trying to do that.
It’s manufacturer specific. What brand is your phone?