QBox: guaranteeing I/O performance on black box storage systems

Many storage systems are shared by multiple clients with different types of workloads and performance targets. To achieve performance targets without over-provisioning, a system must provide isolation between clients. Throughput-based reservations are challenging due to the mix of workloads and the stateful nature of disk drives, leading to low reservable throughput, while existing utilization-based solutions require specialized I/O scheduling for each device in the storage system. Qbox is a new utilization-based approach for generic black box storage systems that enforces utilization (and, indirectly, throughput) requirements and provides isolation between clients, without specializedlow-level I/O scheduling. Our experimental results show that Qbox provides good isolation and achieves the target utilizations of its clients.