. 1 RAID0 at least two hard disks. Throughput, good performance while reading and writing, but the damage will be done a 2 RAID1 at least two hard disks. Quite mirror, a storage, a backup safety is relatively high, but weaker performance than 0 3 raid5 least three hard disks. parity information and data are stored, a bad parity information to be recovered according to 4 . two independent parity system, two disks may be bad, at least four write raid6 disk performance very poor