Voting and Relocation Strategies Preserving Consistency among Replicated Files

Replication can enhance the availability of the data les in a distributed environment. This paper introduces a method for managing replicated data les. Unlike many others, our method provides protocols and algorithms for a more complicated scheme of replication that supports replication with location-variant les and les with a variable degree of replication. We assume the existence of a dynamic le 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 le assignment diier not only in the location of the les 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 les. As a nal result, we show that the interaction between the relocation protocols and these algorithms preserves consistency.