Evaluating quorum systems over the Internet (brief announcement) (original) (raw)
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Evaluating quorum systems over the internet
1996
Quorum systems serve as a basic tool providing a uniform and reliable way to achieve coordination in a distributed system. They are useful for distributed and replicated databases, name servers, mutual exclusion, and distributed access control and signatures.
Evaluating Byzantine quorum systems
… , 2007. SRDS 2007. …, 2007
Replication is a mechanism extensively used to guarantee the availability and good performance of data storage services. Byzantine Quorum Systems (BQS) have been proposed as a solution to guarantee the consistency of that kind of services, even if some of the replicas fail arbitrarily. Many BQS have been proposed recently, but comparing their performance is not simple. In fact, it has been shown that theoretical metrics like the number of steps or communication rounds say as much about the practical performance of distributed algorithms as they hide. This paper presents a comparative evaluation of several BQS algorithms in the literature. The evaluation is based both on experiments and simulations. For that purpose, a framework for evaluating BQS called BQSNeko was developed. The results of the evaluation allow a better understanding of the algorithms and the tradeoffs involved.
The Availability of Quorum Systems
Information and Computation/information and Control, 1995
A quorum system is a collection of sets (quorums) every two of which have a nonempty intersection. Quorum systems have been used for a number of applications in the area of distributed systems.
The Load, Capacity, and Availability of Quorum Systems
SIAM Journal on Computing, 1998
A quorum system is a collection of sets (quorums) every two of which intersect. Quorum systems have been used for many applications in the area of distributed systems, including mutual exclusion, data replication, and dissemination of information.
2010
Abstract This paper outlines a flexible suite of object replication protocols that brings together Byzantine quorum systems registers and state machine replication. These protocols enable the implementation of Byzantine fault-tolerant applications that make minimal assumptions about the environment and that run in at most two more communication steps in almost all cases of non-favorable executions (in comparison with favorable executions).
On a unified framework for the evaluation of distributed quorum attainment protocols
IEEE Transactions on Software Engineering, 1994
Abstmct~uorum attainment protocols are an important part of many mutual exclusion algorithms. Assessing the performance of such protocols in terms of number of messages, as is usually done, may be less significant than being able to compute the delay in attaining the quorum. Some protocols achieve higher reliability at the expense of increased message cost or delay. A unified analytical model which takes into account the network delay and its effect on the time needed to obtain a quorum is presented. A combined performability metric, which takes into account both availability and delay, is defined in this paper, and expressions to calculate its value are derived for two different reliable quorum attainment protocols: Agrawal and El Abbadi's and Majority Consensus algorithms. Expressions for the Primary Site approach are also given as upper bound on performability and lower bound on delay. A parallel version of the Agrawal and El Abbadi protocol is introduced and evaluated. This new algorithm is shown to exhibit lower delay at the expense of a negligible increase in the number of messages exchanged. Numerical results derived from the model are discussed Index Terms-Mutual exclusion, performability, performance analysis, fault-tolerance, distributed systems, delay analysis, majority consensus, tree-based mutual exclusion protocols, primary site protocol.
2014
One of the traditional mechanisms used in distributed systems for maintaining the consistency of replicated data is voting. A problem involved in voting mechanisms is the size of the Quorums needed on each access to the data. In this paper, we present a novel and efficient distributed algorithm for managing replicated data. We impose a logical wheel structure on the set of copies of an object. The protocol ensures minimum read quorum size of one, by reading one copy of an object while guaranteeing fault-tolerance of write operations.Wheel structure has a wider application area as it can be imposed in a network with any number of nodes.
The Load and Availability of Byzantine Quorum Systems
SIAM Journal on Computing, 2000
Replicated services accessed via quorums enable each access to be performed at only a subset (quorum) of the servers, and achieve consistency across accesses by requiring any two quorums to intersect. Recently, b-masking quorum systems, whose intersections contain at least 2b+1 servers, have been proposed to construct replicated services tolerant of b arbitrary (Byzantine) server failures. In this paper we consider a hybrid fault model allowing benign failures in addition to the Byzantine ones. We present four novel constructions for b-masking quorum systems in this model, each of which has optimal load (the probability of access of the busiest server) or optimal availability (probability of some quorum surviving failures). To show optimality we also prove lower bounds on the load and availability of any b-masking quorum system in this model.
Proactive Byzantine Quorum Systems
2009
Byzantine Quorum Systems is a replication technique used to ensure availability and consistency of replicates data even in presence of arbitrary faults. This paper presents a Byzantine Quorum Systems protocol that provides atomic semantics despite the existence of Byzantine clients and servers. Moreover, this protocol is integrated with a protocol for proactive recovery of servers.
Crumbling walls: a class of practical and efficient quorum systems
Distributed Computing, 1997
A quorum system is a collection of sets (quorums) every two of which intersect. Quorum systems have been used for many applications in the area of distributed systems, including mutual exclusion, data replication and dissemination of information In this paper we introduce a general class of quorum systems called Crumbling Walls and study its properties. The elements (processors) of a wall are logically arranged in rows of varying widths. A quorum in a wall is the union of one full row and a representative from every row below the full row. This class considerably generalizes a number of known quorum system constructions.