Automated lookahead data migration in SSD-enabled multi-tiered storage systems

The significant IO improvements of Solid State Disks (SSD) over traditional rotational hard disks makes it an attractive approach to integrate SSDs in tiered storage systems for performance enhancement. However, to integrate SSD into multi-tiered storage system effectively, automated data migration between SSD and HDD plays a critical role. In many real world application scenarios like banking and supermarket environments, workload and IO profile present interesting characteristics and also bear the constraint of workload deadline. How to fully release the power of data migration while guaranteeing the migration deadline is critical to maximizing the performance of SSD-enabled multi-tiered storage system. In this paper, we present an automated, deadline-aware, lookahead migration scheme to address the data migration challenge. We analyze the factors that may impact on the performance of lookahead migration efficiency and develop a greedy algorithm to adaptively determine the optimal lookahead window size to optimize the effectiveness of lookahead migration, aiming at improving overall system performance and resource utilization while meeting workload deadlines. We compare our lookahead migration approach with the basic migration model and validate the effectiveness and efficiency of our adaptive lookahead migration approach through a trace driven experimental study.