The Research Of Reliability Method For Video Store In The Parallel VOD System

With the rapid development of network technology and multimedia technology, network multimedia has been more and more widely applied to our daily life, and among them VOD service is an important item. The VOD system of medium or small size is gradually spreading in use. The improvement of the service quality requires video server —the core of the system is more reliable. The reliability of video server influences the dependence of the whole VOD system, and then influences the service quality. At present, the study of reliability of video server is still in the initial stage. The article mainly studies reliability methods of video store in VOD system.Based on the research of the reliability of other systems, the article presents the following reliable technologies which are suitable for VOD system—improved RAID5 technology, file RAID technology and replication technology.RAID5 technology is a method commonly used to improve the reliability of data. Since the data stored in VOD system is a kind of video stream, we can use an improved RAID5 technology to improve the efficiency of data reconstructing operation in disk failure. Though the buffering of data, the overhead of reading disk could be reduced effectively, and then the efficiency of data reconstruct also could be improved.File RAID is a new technology of data redundant, in file RAID, the file system manages multi-disks and places user data over separate disks redundantly by itself, hence improve the RAID ability. Furthermore, file RAID possesses dynamic choice type. When the disks fail, only allocated portion of space are recovered using parity, which can shorten the time of reconstruct and improve effectively the system reliability.Replication technology is a general method to improve the reliability of data. In view of the particularity of data storage of VOD system what we are studying, we put forward a replication algorithms with forward recovery. This method considers the inefficiency of hardware and guarantees the system approximates the break times of the video and takes over data transmission, which makes the system more reliable.In cluster video server, using cluster technology can guarantee the reliability of system. However, in the cluster, the load may be not well distributed, which is an important factor restricting the whole system. Based on analyzing in details the structure of parallel video server system and synthesizing the methods, which can improve data node reliability, the article brings about a VOD system prototype and a VOD application system.In the end, the article draws a conclusion about the study work and makes a prospect of the study in the next step.