Improving partial stripe write performance in RAID level 5

Redundant Array of Independent Disks (RAID) is now the most efficient way to solve the bottleneck problem between CPU and storage devices. In RAID 5, for the write operation, disk array controller first reads the old data from the disks which the new data will write into and the old parity information. Then, it calculates the new parity information using the old data, the new data and the old parity information to get the new parity. At last, disk array controller writes the new data and the new parity information altogether into the corresponding disks in the array. Thus, in order to write the new data into the disk array, it should perform the two extra read operations and one extra write operation compared with RAID 0. Hence, improving the stripe write operation is the key factor in improving the write performance of RAID 5. The basic idea is the reduce the stripe read/write operations to as few as possible. This paper discusses the different situations of stripe write operation in RAID 5, and proposes an adaptive control algorithm to improve the partial stripe write performance. The basic idea is to reduce the stripe read/write operation as much as possible.