Flavio Junqueira, Ranjita Bhagwan, Alejandro Hevia, Keith Marzullo and Geoffrey M. Voelker Department of Computer Science and Engineering University of California, San Diego
Surviving Internet Catastrophes
In this paper, we propose a new approach for designing distributed systems to survive Internet catastrophes called informed replication, and demonstrate this approach with the design and evaluation of a cooperative backup system called the Phoenix Recovery Service. Informed replication uses a model of correlated failures to exploit software diversity. The key observation that makes our approach both feasible and practical is that Internet catastrophes result from shared vulnerabilities. By replicating a system service on hosts that do not have the same vulnerabilities, an Internet pathogen that exploits a vulnerability is unlikely to cause all replicas to fail. To characterize software diversity in an Internet setting, we measure the software diversity of host operating systems and network services in a large organization. We then use insights from our measurement study to develop and evaluate heuristics for computing replica sets that have a number of attractive features. Our heuristics provide excellent reliability guarantees, result in low degree of replication, limit the storage burden on each host in the system, and lend themselves to a fully distributed implementation. We then present the design and prototype implementation of Phoenix, and evaluate it on the PlanetLab testbed.