A further development of . RAID 6 protects against simultaneous failure of two member disk physical disks by using two independent error correction schemes. Although RAID 6 provides ultra-high data reliability, its write penalty is even more severe than that of RAID 5 because redundant information must be generated and written twice for each application update. As with RAID 4 and RAID 5, the write penalty in RAID 6 is often mitigated by other storage technologies, such as caching.