BPS: A Balanced Partial Stripe Write Scheme to Improve the Write Performance of RAID-6

Nowadays RAID is widely used due to its large capacity, high performance and high reliability. With the increasing requirement of reliability in storage systems and fast development of cloud computing, RAID-6, which can tolerate concurrent failures of any two disks, receives more attention than ever. However, the write performance of RAID-6 systems is a bottleneck to serve various applications. In the last two decades, many approaches are proposed to enhance the write performance of RAID-6, but they have several limitations, such as unbalanced I/O distribution and high I/O cost. To address this problem, in this paper, we propose a Balanced Partial Stripe (BPS) write scheme to improve the write performance of RAID-6 systems. The basic idea of BPS is reorganizing the distribution of write data blocks according to a global point of view on modified parities, and flushing these blocks to storage devices at once. Therefore, it can significantly reduce the total number of parity updates and balance the I/O workload. BPS has three main advantages: 1) BPS decreases the number of I/O operations and aggregate the fragmented I/Os, which improves the I/O performance, 2) BPS provides a balanced partial stripe write approach for RAID-6, 3) BPS can be applied with various erasure codes. To demonstrate the effectiveness of our scheme, we conduct simulations on DiskSim to evaluate different partial stripe write approaches. The results show that, compared to typical partial stripe write approaches, BPS reduces the average access time by up to 37.14%, and decreases the number of write operations by up to 26.24%.