Comparison of distance limiting methods for risk-aware data replication in urban and suburban area

Risk-aware data replication (RDR), which replicates data at primary sites to safe backup sites, has been proposed to mitigate a service disruption in a disaster area even after a widespread disaster that damages a network and a primary site. RDR assigns a safe backup site to a primary site while considering a damage risk for both the primary site and the backup candidate site. When the backup candidate sites are widely distributed in an urban and suburban area, RDR sometimes assigns a backup site too far from the primary site. However the backup site is desired to be reachable from the primary site by physical transfer such as walking, bicycle, car, or drone in case that a severe disaster damages network among the sites. Therefore, limiting the distance between the primary site and the backup site is required. To approach this challenge, we propose two possible methods: the average distance limiting (ADL) method and the maximum distance limiting (MDL) method. In this paper, we compare the distance distributions, the data availability, and the computation time of two methods. Then, we conclude that the MDL method is the most practicable from a comprehensive perspective.