Replication Based QoS Framework for Flash Arrays

The increasing popularity of the storage cloud is leading organizations to move their applications and enterprise data into the cloud. It is desirable to move time-critical applications demanding high performance I/O operations. Flash based storage arrays have emerged to address the high performance I/O requirements, however, providing predictable Quality of Service (QoS) for applications with real time data requirements is a challenging open problem. This paper introduces a QoS framework for flash based storage arrays. Our framework provides deterministic and statistical response time guarantees through a combination of techniques including replication, data mining, and online retrieval. We evaluated the framework using synthetic and real-world traces. The QoS performance of the system is compared to the existing high-throughput RAID designs. Numerical results show that under the synthetic traces, QoS performance of the proposed system outperforms the existing high performance RAID designs. Real world traces indicate that the proposed QoS mechanism is tunable to support the guarantees required by various real world applications.