Some results on quadrilaterals in Steiner triple systems
Discrete Mathematics
A N algorithm for mutual exclusion in decentralized systems
ACM Transactions on Computer Systems (TOCS)
The availability of quorum systems
Information and Computation
Load Balancing in Quorum Systems
SIAM Journal on Discrete Mathematics
The Grid Protocol: A High Performance Scheme for Maintaining Replicated Data
Proceedings of the Sixth International Conference on Data Engineering
Two New Quorum Based Algorithms for Distributed Mutual Exclusion
ICDCS '97 Proceedings of the 17th International Conference on Distributed Computing Systems (ICDCS '97)
Quorum-based asynchronous power-saving protocols for IEEE 802.11 ad hoc networks
Mobile Networks and Applications
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A quorum system is a set system in which any two subsets have nonempty intersection. Quorum systems have been extensively studied as a method of maintaining consistency in distributed systems. Important attributes of a quorum system include the load, balancing ratio, rank (i.e., quorum size), and availability. Many constructions have been presented in the literature for quorum systems in which these attributes take on optimal or otherwise favorable values. In this paper, we point out an elementary connection between quorum systems and the classical covering systems studied in combinatorial design theory. We look more closely at the quorum systems that are obtained from balanced incomplete block designs (BIBDs). We study the properties of these quorum systems and observe that they have load, balancing ratio, and rank that are all within a constant factor of being optimal. We also provide several observations about computing the failure polynomials of a quorum system (failure polynomials are used to measure availability). Asymptotic properties of failure polynomials have previously been analyzed for certain infinite families of quorum systems. We give an explicit formula for the failure polynomials for an easily constructed infinite class of quorum systems. We also develop two algorithms that are useful for computing failure polynomials for quorum systems and prove that computing failure polynomials is #P-hard. Computational results are presented for several "small"quorum systems obtained from BIBDs. Copyright 2001 Academic Press.