DURO: A New Online Reconstruction Optimization For Single-disk-failure Of RAID-6

With the rapid development of computer science and technology,the total amount of data is growing at a exponential rate. Turing Award winner Jim Gray proposed a piece of new experience laws: In a network environment, the amount of data generated every 18 months is equal to the sum of historical data. At the same time, the data's role in social production is getting more and more attention. The 21st century, is not only a data explosion era, but a data-oriented era. Therefore, the avilability and reliability of the informatino storage system are particularly important. RAID is a major program of block-level storage technology. Among them, a double-disk fault-tolerant RAID-6 has wide applications. The reliability of RAID-6 is affected by the number of disks, reconstruction time and other factors. After analyzing the all existing reconstruction models, we design a new reconstruction strategy to reduce the online-reconstruction time. It can improve reliability of strorage system, reduce the probability of data loss.This paper presents a new strategy for online reconstruction of single-disk failure for RAID-6---- DURO (Detach User I/O and Reconstruction I/O Optimization). DURO takes advantages of double-disk failure tolerance ability of RIAD-6, and changes the "single disk failure" into a "double-disk failure", and physically separates the user work flow from work flow reconstruction. DURO not only eliminates the inter-influence between the two work flows, but also increases the data transferring bandwidth of RAID-6. It guarantes response time of user requests, and reduces online-reconstruction time of single-disk failure for RAID-6. DURO online-reconstruction time is determined by the disk number and disk access speed, which is independent of the user workflow. During reconstruction, the response time of user requests is not influenced by reconstructing speed. In heavier user workflow environment, DURO can guarantee a certain bandwidth for reconstruction work flow, and reduce reconstruction time and response time of user requests.Theoretics analysis and experimentally results show that DURO outperforms traditional reconstruction method in reconstruction time and average response time of user requests.