> OK here is the deal, RAID5 uses ONLY ONE parity drive per stripe
In RAID-6 you have multiple redundancy, so the probability of complete failure can be arbitrarily reduced. However, most people go with RAID-5 because they haven't got enough disks for RAID-6 to make sense, whereas if you have loads (like Backblaze for instance using 3 parity out of 15 disks) then it does make sense.
> OK here is the deal, RAID5 uses ONLY ONE parity drive per stripe
In RAID-6 you have multiple redundancy, so the probability of complete failure can be arbitrarily reduced. However, most people go with RAID-5 because they haven't got enough disks for RAID-6 to make sense, whereas if you have loads (like Backblaze for instance using 3 parity out of 15 disks) then it does make sense.