Optimizing the performance of quorum consensus replica control protocols

The research results on replica control protocols that are based on quorum consensus are summarized. In quorum consensus methods, operations to obtain permission from a quorum group of nodes to proceed to completion are required, and the collection of quorum groups is called a quorum set. The techniques developed for finding the quorum set that maximizes a given performance measure are presented. The optimality of voting, a replica control protocol that can effectively reduce response time through load sharing, and the multidimensional voting (MD) technique, which can be used to define all quorum sets, are briefly discussed. An MD-voting-based implementation of a dynamic quorum consensus protocol that allows the synchronization procedure to adapt to the current state of the system is described