A realistic evaluation of optimistic dynamic voting

When data are replicated an access protocol must be chosen to ensure 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. A dynamic voting protocol that does not need the instantaneous state information required by the original dynamic voting proposal is described. It provides the same performance as the original dynamic voting in the asymptotic case and quickly converges to it for realistic access rates, at a cost in network traffic similar so that of static majority consensus voting. The availability afforded by dynamic voting protocols is analyzed, taking the access frequency into account. The analysis confirms the hypothesis that delaying state information does not appreciably affect availability. Discrete event simulation is used to confirm and to extend the analytical results