Replica Stragegy Research Based On P2P Distributed Storage System

The explosive growth of various data promotes computer storage technology to develop rapidly. Compared with the traditional C/S mode, P2P storage systems make full use of decentralized users’resources. Consequently, it gets a lot of attention for its open, safety, flexible expandability and so on.As an important part of P2P storage system, replica strategy can improve the extensibility, usability, fault tolerance and reduce query response time. But increasing the number of replicas may bring about replicas management problems. At present, there are some questions as follows. At first, when replica is created, the unreasonable decision of storage locations and quantity can result in consumption of storage resources and network bandwidth. At the same time, replica consistency algorithms can not guarantee to reduce redundant update messages and update replicas on time. This paper researches on the above problems.On replication strategies, the paper proposes an access frequency replication algorithm based on cluster topology. At first, it partitions the network into clusters by network distance. And a cluster head is choosed by the same way as super node selection. Cluster-members and cluster-heads are managed by Chord protocol. Due to close network distance, a cluster is looked as a unity, which can reduce access time delay, improve query efficiency and data transmission rate. Based on access frequency replication strategy can copy popular data and place it in reasonable position. Consequently, it can reduce the bandwidth consumption caused by remote access. Experimental results verify that the algorithm can effectively reduce the network costs and remote data access.In addition, the paper proposes a node heterogeneous degree-based replica consistency maintance algorithm for overlay network. Based on Chord group management protocols, we present a partition method by the finger table to solve the problem of node information acquisition. Considering the node heterogeneity, the authors put forward the concept of heterogeneous degrees nodes and construct heterogeneous degrees collection tree. Last but not least, it gets minimum delay content updates tree content update tree by dynamic programming algorithm. Theoretical analysis and simulation results show that node heterogeneous replica consistency maintenance algorithm can reduce redundant message effectively and update replica quickly.