Replication Strategies Research On Data Management For WAN Storage Service

The rapid development of network tech brings quick increase of the information transferred by network. The next generation of the Internet put forward the new requirement of network storage in storage capacity, security, reliability and usability. The research on network storage system is becoming a new hotspot in computer architecture.The Storage Service USTOR (Ubiquitous Storage) for the Next Generation Internet is set up in IPv6 WAN, which supports the total storage capacity of PB class and at least 256 distributed nodes. The system is divided into such four parts as the storage management, data management, load balance strategy and the data transfer middleware. To keep the vitality of the system, optimize the distribution of the storage resource and express the value of the data, we provide data management in USTOR.Replica is one way, which implements such two kinds of method as replication and migration in data management. The replica strategy in USTOR can manage the share of users efficiently and improve the QOS of the storage service. Replica strategy is composed of qualification of the replica creation and deletion settings, replica quantity management, concurrency control and so on. Dynamic replica management based on access frequency is implemented in USTOR.With different scan cycle settings and placement strategy, we give a contrast test with traditional replica strategy on the performance of the system. And the results show that with variable scan cycle and directional placement strategy, replica manager can give response to the change of the access frequency more quickly, shorten the average response time in file access more availably and provide higher quality of the storage service.