Enhancing write I/O performance of disk array RM2 tolerating double disk failures

With a large number of internal disks and the rapid growth of disk capacity, storage systems become more susceptible to double disk failures. Thus, the need for such reliable storage systems as RAID6 is expected to gain in importance. However RAID6 architectures such as RM2, P+Q, EVEN-ODD, and DATUM traditionally suffer from a low write I/O performance caused by updating two distinctive parity data associated with user data. To overcome such a low write I/O performance, we propose an enhanced RM2 architecture which combines RM2, one of the well-known RAID6 architectures, with a Lazy Parity Update (LPU) technique. Extensive performance evaluations reveal that the write I/O performance of the proposed architecture is about two times higher than that of RM2 under various I/O workloads with little degradation in reliability.