Abstract: In order to meet the needs of various users for cloud storage,cloud storage service providers generally divide the data into fixed size block and use redundancy backup technology to store data.So the researches on storage mechanism of the block placement,the best replica selection and the replica size have always been hot spots in improving the transmission speed of big file.According to the heterogeneity of storage nodes in cloud storage system,the improved strategy which uses AHP to weight the index of node performance,and uses the weighted index to improve particle swarm optimization algorithm(AHPPSO) was proposed.By introducing the weighted evaluation matrix associated with the performance of the storage node,PSO evolves toward the node of high comprehensive performance,improving the data transmission speed without increasing the cost of storage space.The strategy was realized in a self-built cloud sto-rage system,and the experiment result shows that this strategy can adapt to the various needs of users,and achieve the system load balancing to a certain extent.

Key words: Cloud storage,Heterogeneity,Particle swarm algorithm,AHP,Load balancing