Thwarting Virtual Bottlenecks in Multi-Bitrate Streaming Servers

Current cycle-based disk IO schedulers for multi-bitrate streaming servers are unable to avoid the formation of virtual bottlenecks. We term a bottleneck as virtual when it occurs within a single resource subsystem, and it is possible to use a secondary under-utilized resource to thwart the bottleneck. We present stream combination, an IO scheduling technique that addresses this problem. Stream combination predicts the formation of virtual bottlenecks and proactively alters the IO schedule to avoid them. A simulation study suggests significant performance gains compared to the current state-of-theart fixed time-cycle IO scheduler.