Rice Software Consulting
The authors present a novel QoS scheduling algorithm for multi-tiered storage servers made up of hard disks and SSDs. The work is motivated by the difference in access times for a workload as its SSD hit ratio changes. The authors' scheme is designed to reward clients according to their runtime behavior, while honoring their static QoS settings including shares (or weights), reservations and limits. A model based on entitlements is developed to describe the Reward Allocation Policy (RAP).