UC Santa Cruz

When data is replicated, an access protocol must be chosen to insure the presentation of a consistent view of the data. Protocols based on quorum consensus provide good availability with the added benefit of mutual exclusion. Of the protocols based on quorum consensus, the dynamic voting protocols provide the highest known availability. We describe a dynamic voting protocol that does not need the instantaneous state information required by the same performance as the original dynamic voting in the asymptotic case, and quickly converges to it for realistic access rates. Our protocol does this at a cost in network similar to that of statistic majority consensus voting. The first realistic analysis of the availability afforded by dynamic voting protocols is presented, taking the ac- cess frequency into account. The analysis confirms our hypothesis that delaying state information does not appreciably affect availability. Discrete event simulation is used to confirm and to extend the results we obtain using analytic models.