The theoretical analysis of R-fold modular redundancy with distributed voters - distributed R-fold modular redundancy in terms of reliability is presented for the first time to the best of author's knowledge. This technique is compared in terms of resistance to massive levels of defect density expected in future nano-devices to R-fold modular redundancy with a single voter, cascaded R-fold modular redundancy and NAND multiplexing. Optimal partition size analysis and redundancy optimization of distributed R-fold modular redundancy technique has been performed for the first time in the context of a large-scale system. The optimal window of application of different fault-tolerant techniques with respect to defect density, is presented as a way to find the optimum design trade-off between the reliability and power/area.