DRACON: QoS Management for Large-Scale Distributed Real-Time Databases

The demand for real-time data services is increasing in many large-scale distributed real-time applications including advanced traffic control, global environment control, and the nation-wide electric power grid control. However, providing quality-of-service (QoS) for data services in such large-scale and geographically distributed environment is a challenging task. In particular, both unpredictable communicational delays and computational workloads of large-scale distributed systems can lead to large number of deadline misses. We have designed a distributed real-time database architecture called DRACON (Decentralized data Replication And CONtrol), which enables QoS guarantees for large-scale distributed real-time applications. DRACON couples cluster-based replica-sharing and a decentralized control structure to address communication and computational unpredictability, simultaneously. The cluster-based replica-sharing mechanism not only enables scalable and bounded-delay access to remote data with high probability, but also decouples clusters to have less interaction, allowing a decentralized, thus scalable, QoS control structure. The simulation study demonstrates that DRACON’s decentralized QoS control structure combined with a decentralized replica-sharing structure provides robust and predictable QoS guarantees in a highly scalable manner.