An ordered, comma-separated list of key-value pairs that describe the topography of the machine. Topography might include country, datacenter or rack designations. Data is automatically replicated to maximize diversities of each tier. The order of tiers is used to determine the priority of the diversity, so the more inclusive localities like country should come before less inclusive localities like datacenter. The tiers and order must be the same on all nodes. Including more tiers is better than including fewer. For example:
country=us,region=us-west,datacenter=us-west-1b,rack=12
country=ca,region=ca-east,datacenter=ca-east-2,rack=4
planet=earth,province=manitoba,colo=secondary,power=3