Heidi Howard
Jon Crowcroft
ABSTRACT
Distributed consensus is fundamental in distributed systems for achieving fault-tolerance. The Paxos algorithm has long dominated this domain, although it has been recently challenged by algorithms such as Raft and Viewstamped Replication Revisited. These algorithms rely on Paxos's original assumptions, unfortunately these assumptions are now at odds with the reality of the modern internet. Our insight is that current consensus algorithms have significant availability issues when deployed outside the well defined context of the datacenter. To illustrate this problem, we developed Coracle, a tool for evaluating distributed consensus algorithms in settings that more accurately represent realistic deployments. We have used Coracle to test two examples of network configurations that contradict the liveness claims of the Raft algorithm. Through the process of exercising these algorithms under more realistic assumptions, we demonstrate wider availability issues faced by consensus algorithms when deployed on real world networks.
- H. Howard, M. Schwarzkopf, A. Madhavapeddy, and J. Crowcroft. Raft refloated: Do we have consensus? ACM SIGOPS Operating Systems Review, 49(1):12--21, 2015. Google Scholar
Digital Library
- L. Lamport. The part-time parliament. ACM Transactions on Computer Systems (TOCS), 16(2):133--169, 1998. Google ScholarDigital Library
- B. Liskov and J. Cowling. Viewstamped replication revisited. 2012.Google Scholar
- D. Ongaro and J. Ousterhout. In search of an understandable consensus algorithm. In USENIX Annual Technical Conference. Google ScholarDigital Library
- F. B. Schneider. Implementing fault-tolerant services using the state machine approach: A tutorial. ACM Computing Surveys (CSUR), 22(4):299--319, 1990. Google ScholarDigital Library
Index Terms
- Coracle: Evaluating Consensus at the Internet Edge
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