Replicated Data Management in Mobile Environments: Anything New Under the Sun?

Abstract

The mobile wireless computing environment of the future will contain large numbers of low powered palmtop machines. Replication will be an essential technique in this environment, providing data availability to the system. In a mobile environment it is important to have dynamic replicated data management algorithms that allow for instance copies to migrate from one site to another or for new copies to be generated. In this paper we show that such dynamic algorithms can be obtained simply by letting transaction update the directory that specifies sites holding copies. Thus we argue that no fundamentally new algorithms are needed to cope with mobility. However, exisiting algorithms may have to be "tuned" for a mobile environment, and we discuss what this may entail. As an illustration, we present a variation of the primary copy algorithm, Primary By Row, that is well suited for migrating copies 1 . Keywords: Distributed Data Bases, replication, mobility, availability.