An Improvement of Migration Efficiency in a Distributed Storage System with Dynamic Tiering

We have proposed a distributed storage system which autonomously migrates a data block into a suitable storage node. In our storage system, heavily accessing data blocks will be migrated autonomously to a higher performance storage node (i.e. an upper storage tier), and rarely accessed data blocks will be migrated to a lower performance storage node (i.e. a lower storage tier). Our investigation shows that it may need several migrations in order to locate a data block onto the most suitable storage node when the destination storage tier has a lot of storage nodes. In this paper, we propose a method to enhance data migration efficiency to improve I/O performance of the whole system. Our simulation results show that the proposed method can greatly reduce I/O execution time than the previous one. The execution time was reduced about one-fifth at the maximum in a system with several hundred scale nodes.