172447
20181203022558.0
doi
10.1007/s00446-010-0103-7
ISI
000280921100001
ARTICLE
Refined quorum systems
2010
2010
Journal Articles
It is considered good distributed computing practice to devise object implementations that tolerate contention, periods of asynchrony and a large number of failures, but perform fast if few failures occur, the system is synchronous and there is no contention. This paper initiates the first study of quorum systems that help design such implementations by encompassing, at the same time, optimal resilience, as well as optimal best-case complexity. We introduce the notion of a refined quorum system (RQS) of some set S as a set of three classes of subsets (quorums) of S: first class quorums are also second class quorums, themselves being also third class quorums. First class quorums have large intersections with all other quorums, second class quorums typically have smaller intersections with those of the third class, the latter simply correspond to traditional quorums. Intuitively, under uncontended and synchronous conditions, a distributed object implementation would expedite an operation if a quorum of the first class is accessed, then degrade gracefully depending on whether a quorum of the second or the third class is accessed. Our notion of refined quorum system is devised assuming a general adversary structure, and this basically allows algorithms relying on refined quorum systems to relax the assumption of independent process failures, often questioned in practice. We illustrate the power of refined quorums by introducing two new optimal Byzantine-resilient distributed object implementations: an atomic storage and a consensus algorithm. Both match previously established resilience and best-case complexity lower bounds, closing open gaps, as well as new complexity bounds we establish here. Each of our algorithms is representative of a different class of architectures, highlighting the generality of the refined quorum abstraction.
Quorums
Atomic storage
Consensus
Complexity
Byzantine failures
Consensus
Objects
Memory
Paxos
Time
240335
Guerraoui, Rachid
105326
Ecole Polytech Fed Lausanne, Sch Comp & Commun Sci, CH-1015 Lausanne, Switzerland
Vukolic, Marko
IBM Res Zurich, Ruschlikon, Switzerland
23
1-42
Distributed Computing
252114
DCL
U10407
oai:infoscience.tind.io:172447
IC
article
EPFL-ARTICLE-172447
EPFL
REVIEWED
PUBLISHED
ARTICLE