MDR Codes: A New Class of RAID-6 Codes with Optimal Rebuilding and Encoding

摘要

As storage systems grow in size, device failures happen more frequently thanever before. Given the commodity nature of hard drives employed, a storagesystem needs to tolerate a certain number of disk failures while maintainingdata integrity, and to recover lost data with minimal interference to normaldisk I/O operations. RAID-6, which can tolerate up to two disk failures withthe minimum redundancy, is becoming widespread. However, traditional RAID-6codes suffer from high disk I/O overhead during recovery. In this paper, wepropose a new family of RAID-6 codes, the Minimum Disk I/O Repairable (MDR)codes, which achieve the optimal disk I/O overhead for single failurerecoveries. Moreover, we show that MDR codes can be encoded with the minimumnumber of bit-wise XOR operations. Simulation results show that MDR codes helpto save about half of disk read operations than traditional RAID-6 codes, andthus can reduce the recovery time by up to 40%.