Which RAID configuration should I go with for fault-tolerance?

"Raid 10 is better than raid5

Raid 5 you can lose at most one disk
Raid 10 you can lose two disks as long as they're not from the same pair
Raid 10 is faster

Personally, I feel raid5 is a bit of a waste on 4 disks - it leaves you with the capacity of n-1 disks whereas raid10 gives you a capacity of n/2 disks. If you have 10 disks then there's a sigificant amount of space lost by choosing raid10, but with 4 disks it's not nearly as significant.

If you can afford to give up the extra space then go with raid 10."