Abstract: Data replica management is an important component in cloud storage system,which is important for improving the system reliability and high performance．In general,if the number of replicas increase,the transfer cost will be declined because of the data can transfer more effectively；but the storage cost is becoming large because of the existence of additional replicas．Aimed to reduce the cost of data management,this paper proposed a minimum-cost based data replication strategy in balancing storage cost and transfer cost,including the data management cost model,the necessity of adding data replica and an approximate algorithm that can automatically decide the number and their store places．Both the theoretical analysis and simulations conducted on general (random) data sets as well as specific real world applications with Amazon’s cost model show that the minimum-cost replica strategy is close to or even the same as the minimum cost benchmark and the efficiency is very high for practical runtime utilization in the cloud．On the other side,this research can promote the enterprise (user) actively using cloud computing platform and the harmonious development of cloud computing environment.

Key words: Cloud computing,Replication management,Minimum-cost