An Energy-Aware File Relocation Strategy Based on File-Access Frequency and Correlations

Energy consumption has become a big challenge of the traditional storage systems due to the explosive growth of data. A lot of research efforts have been invested in reducing the energy consumption of those systems. Traditionally, the frequently accessed data are concentrated into a small part of hot storage nodes, and other cold storage nodes are switched to a low-power state, thus saving energy. However, due to the energy penalty and time penalty, it takes extra energy and generates additional delay to switch a cold storage node from a low-power state to an active state. In contrast to the existing work, this paper proposes a Skew File Relocate (SFR) strategy which aggregates the correlated cold files to the same cold storage node in addition to concentrating the frequently accessed files to the hot nodes. Because the correlated files are normally accessed together, SFR can significantly reduce the number of power state transitions and lengthen the idle periods that the cold storage nodes are experienced, thus saving more energy and improving the system response time. Furthermore, other three relocation strategies are designed to explore the performance behavior of SFR. Experimental results demonstrate that SFR can significantly reduce the energy consumption while maintaining the system performance at an acceptable level.