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A Method of Adjusting the Number of Replica Dynamically in HDFS

With the development of Cloud Computing, Hadoop –an Infrastructure as a Service open source project of Apache – has been used more and more widely. As the basis of Hadoop, the Hadoop Distributed File System (HDFS) provides basic function of file storage. HDFS-an open source implementation of Google File System (GFS) –was designed for specific demand. Once the demand was changed, HDFS cannot fit it very well. Especially when the access demand of file is different, there will be hot spots and the existing replica will not be enough. It will lower the efficiency of the whole system. This paper introduced a systemlevel strategy which could adjust the replica number of specific file dynamically. And the experiment shows that this mechanism can prevent the problem of decline of user experience bring by hot spots and improve the overall efficiency.