RAID5 is indeed too dangerous to use, for the reason Tom has explained. That's why a lot of 'hardcore' home users started using RAID6, where two drives may fail. This is course doesn't help with the slow rebuild times and scrubbing etc... It also means you'll need at least 4 drives and a lot of drive space simply for parity calculations so you won't have that much free space left. (if you only use 4 disks, you'll loose half of your disk capacity, which makes it rather costly)
The thing about "4 drives" is that this is often the limit for an enclosure or chassis. Sure, there are larger (and smaller) units, but four is pretty common.
So with four drives, just use two of them straight-up (or with mhddfs), and then use the other two as 100% backup copies.
So two data drives, and a full backup. Obviously better than RAID6 w/o a backup, and better than RAID1, because errors/deletions don't get mirrored until you tell them to get mirrored.
Previous Topic
Index
