A proposal for method of hybrid storage system to improve sequential access transfer rate for workloads with low access locality

A method of hybrid storage system consisting of HDD and SSD for workloads with low access locality is proposed. In case of low access locality, it is difficult to improve transfer rate by existing methods of hybrid storage systems such as cache or tiering methods. The proposed method stores the head portion of the files into SSD, so the time for reading the head portion of the files can overlap the time for justification of magnetic head in HDD. Because of this, transfer rate can be improved to reduce the time of reading whole length of file. In this paper, we assume practical access locality and evaluate transfer rate of the proposed method and that of the existing methods. As a result, the proposed method has an advantage over existing methods when average file size is around 10MB under low access locality such as video sharing.