Cinematic-Quality VoD in a P2P Storage Cloud: Design, Implementation and Measurements

In this paper, we explore the design space and practice of a new peer-to-peer (P2P) storage cloud, which is capable of replicating, refreshing and on-demand streaming of cinematic-quality video streams, in a decentralized fashion using local storage spaces of end users. We identify key design challenges and tradeoffs in such a P2P storage cloud, and how these are addressed by making informed design choices in a step-by-step fashion. Following our design choices, we have implemented a real-world Video-on-Demand (VoD) system with over 100,000 lines of code, called Novasky, which features new coding-aware peer storage replacement and server push-to-peer strategies, in order to maintain media availability and to balance the system-wide supply-demand relationship in the P2P storage cloud. Since September 2009, it has been deployed in the Tsinghua University campus network, attracting 10,000 users during our measurement studies from February to July 2010, and providing over 1,000 cinematic-quality video streams with bit rates of 1 - 2 Mbps. Based on real-world traces collected over 6 months, we show that Novasky can achieve rapid startups within 4 - 9 seconds and extremely short seek latencies within 3 seconds, while maintaining reasonable operational overhead and server bandwidth costs. Our general understanding on the design tradeoffs of P2P storage cloud and practical experiences with Novasky may bring valuable guidelines to future designs of production-quality P2P storage cloud systems.