Analysis of a dynamic voting algorithm based on regeneration with virtual copies

A consistency control algorithm for replicated data objects in distributed computing systems, called RVC2, has been extensively analyzed. RVC2 is a voting-based algorithm which utilizes a selective regeneration and recovery mechanism for failed copies of data objects. Virtual copies, which record information about the current state of a copy, but which contain no actual data, are used in addition to real copies to reduce network and storage overhead. Empirical results concerning availability, obtained through simulation, are presented. These results show that varying the number of real versus virtual copies, and varying the generation threshold, has no significant impact on availability. The results also suggest that RVC2 is an unnecessarily complex algorithm because regeneration has no significant impact on availability under most circumstances