Voting and Relocation Strategies Preserving Consistency among Replicated Files

Abstract

Replication can enhance the availability of the data files in a distributed environment. This paper introduces a method for managing replicated data files. Unlike many others, our method provides protocols and algorithms for a more complicated scheme of replication that supports replication with location-variant files and files with a variable degree of replication. We assume the existence of a dynamic file assignment algorithm as well as a block-oriented majority consensus voting approach. This paper investigates how to maintain consistency during relocation, if the current and the new file assignment differ not only in the location of the files but also in the number of replicas. We introduce the basic relocation protocols to preserve consistency during relocation and present the read- and write-block algorithms for accesses to data blocks of transient files. As a final result, we show that the interaction between the relocation protocols and these algorithms preserves consistency. ..