Research And Implementation Of The Key Technology In RAID System Based On Video

At present, the problem of the storage barrel of the video on demand (VOD) is getting more and more obvious with the wide use of the video digitization's technology. Adopting the RAID technology is a good way to solve the problem, so the use of RAID in video on demand is becoming a critical technology in the field of video.Some key technologies have been analyzed,such as the architecture of the storage system in the video servers, the disk scheduling policies of video stream and the ways of the data arrangement. Furthermore, the realizing mechanism and disadvantages of the real time of soft Raid based on Linux system have also been discussed. Based on the all above, a kind of Raid system with high performance and good scalability based on the disk sub system has been designed,and several key technologies which can improve the performance of the storage I/O have been studied. The key technologies are as follows: first, there are not any memory copying operations in the read-write request process by using the technology of memory zero copying. Second, a special buffer cache is adopted to improve the performance of Raid and introduced a larger data block unit in the buffer cache, and the searching speed of the request in the cache has been greatly improved by using the way of AVL. Third, the conflict detection mechanism is used to solve the problem which several requests access the same stripe in RAID. At last, there are two scheduling method to improve the system performance. one is optimizing the ways of disk head's operation, and the other is that several requests which access some sequential sectors in the same disk is combined to a larger request.Finally, through the performance testing experiments comparing with the soft Raid system based on Linux 2.4.18, it has been proved that the system which we have designed can improve the performance of I/O greatly and satisfy the expected requirement.