Design Of Virtual Disk Module And Research Of Fault-resistance Technology For Raid System

Technology of information storage becomes more and more important as information technology develops faster than ever before. Relying on their own data information, increasing companies make their decision with the help of frequent and efficient support. Furthermore, the security of data information is far more significant to certain industries like telecom and finance because abundant storage information and management data come into being at every moment. However, the development speed of storage system is relatively slower than that of CPU, which forms the bottleneck of computer performance. As a result, redundant arrays of independent disks (RAID) covers a potentially huge market for its high effect in improving the performance of storage system.Virtual disk module (Vdisk) is the most important module in the whole RAID system. Vdisk module controls the distribution of information data and parity data in physical disks according to different RAID level or new RAID arithmetic. When there is new write or read task in the system, Vdisk is responsible for the address mapping between virtual disk and physical disk. Furthermore, Vdisk takes charge of the reconstruction of disks and the rebuild of data when certain disks are out of work, which is capability in handling abnormal situation. So, it is vital to design Vdisk well because it directly results in the fault-resistance performance of RAID.Firstly, this paper briefly introduces RAID system and the function and importance of virtual disk module. Secondly, it analyzes some normal RAID level according to Vdisk and several fault-resistance technology and method in RAID, introducing some popular technology and its corresponding rebuild technology. Thirdly, it focus on the high level RAID system----RAID 5EE, especially the improvement of fault-resistance technology and its system realization. Finally, this paper proposes a novel triple parity placement scheme----HDD, which uses, in a single disk partition, horizontal parity, first diagonal parity and second diagonal parity to store the redundant information. This scheme enables a RAID to recover rapidly from up to three disk failures, to enhance the reliability of a RAID system. The result of performance analysis shows that HDD has satisfying behavior in coding and decoding rate, access speed in small data and data redundancy.