Predicting node availability in peer-to-peer networks
James W. Mickens, Brian D. Noble · 2005
Unlike the well-administered servers in traditional distributed systems, machines in peer-to-peer networks have widely varying levels of availability. Accurate modeling of node uptime is crucial for predicting per-machine resource burdens and selecting appropriate data replication strategies. In this research project, we improve upon the accuracy of previous peer-to-peer availability models, which are often too conservative to dynamically predict system availability at a fine-grained level. We test our predictors on availability traces from the PlanetLab distributed test bed and the Microsoft corporate network. Each trace has a distinct predictability profile, and we explain these differences by examining the fundamental uptime classes contained in each trace. We also show how availability-guided replica placement reduces the amount of object copying in a distributed data store.