Abstract

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. A theoretical analysis of the algorithm under normal and exceptional conditions, in terms of the message cost, is presented. The results show that RVC2 has a high message cost under some conditions. Empirical results concerning availability, obtained through simulation, are also discussed. 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. 1.

Citations