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Dynamic data replication on flash SSD assisted Video-on-Demand servers

Flash memory based SSD (solid state disk) has quick access time, which make it an attractive storage device for read-intensive applications like VoD (Video-on-Demand). However, flash SSD is much more expensive than HDD (hard disk drive). Thus, we propose a hybrid storage architecture that integrates small capacity flash SSDs into HDDs to form a high-performance and cost-effective storage subsystem for VoD servers. Further, on top of the hybrid storage architecture, a dynamic data replication strategy called FLARE (flash for replication) has been developed. Inspired by the insights of a recent user behavior investigation on a large-scale VoD system, FLARE only makes replicas for the first several minutes of a popular video file. A comprehensive simulation study using a real-world trace on a validated disk simulator demonstrates that FLARE consistently performs better than conventional pure HDD based data striping.