Abstract

In a new algorithm for maintaining replicated data, every copy of a replicated file is assigned some number of votes. Every transaction collects a read quorum of r votes to read a file, and a write quorum of w votes to write a file, such that r+ w is greater than the total number of votes assigned to the file. This ensures that there is a non-null intersection between every read quorum and every write quorum. Version numbers make it possible to determine which copies are current. The reliability and performance characteristics of a replicated file can be controlled by appropriately choosing r, w, and the file's voting configuration. The algorithm guarantees serial consistency, admits temporary copies in a natural way by the introduction of copies with no votes, and has been implemented in the context of an application system called Violet. Key Words and Phrases: weighted voting, replicated

Citations

289	A majority consensus approach to concurrency control for multiple copy databases - Thomas - 1979
91	Concurrency control and consistency of multiple copies of data in distributed ingres - Stonebraker - 1979
36	Mesa language manual - Mitchell, Maybury, et al. - 1979
29	Notes on Data Base Operating Systems, Operating Systems, An Advanced Course - Gray - 1978
14	Separating data from function in a distributed file system - srael, Mitchell, et al.
13	et al. The Notions of Consistency and Predicate Locks in a Database System - Eswaran - 1976
5	et al. Granularity of Locks and Degrees of Consistency in a Shared Data Base - Gray, Lorie, et al. - 1976
2	An Experimental Decentralized System, Integrated Office System Workshop - Gifford - 1979
1	Available as CSt Report 79-12, Xerox Pal Alto Roemob Canter - Nv - 1979
1	Experience with Processes and Monitors in Mesa, to appear - Lampson, Redell
1	Crash Recovery in a Distributed Data - Lampson, Sturgis
1	The Redundant Update Methodology ofSDD-I: A System for Distributed Databases (The Fully Redundant - Rothnie, Goodman, et al. - 1977