A fault tolerant (√N) algorithm for distributed mutual exclusion

A low-cost and highly tolerant protocol for distributed mutual exclusion is presented. This protocol logically organizes nodes as a √N×√N grid. The smallest quorum size of the protocol is O(√N). The system model is given. The definition of a quorum is provided. The proof of correctness of the protocol is given. The authors present an algorithm to implement the protocol in distributed systems. They show that every quorum of M. Maekawa´s algorithm (1985) and every quorum of the grid protocol (S.Y. Cheung et al., 1990) are also quorums of the protocol. The protocol can survive even if [(√N-1)/2] columns of nodes in the grid have failed. Computations comparing the fault tolerance of the protocol with that of Maekawa´s algorithm and the grid protocol are included