1. A computer-implemented method for generating replication requests for objects in a distributed storage system, comprising: at a computer system including one or more processors and memory storing one or more programs, for execution by the one or more processors: generating replication requests for objects in a distributed storage system based at least in part on replication policies for the objects and a current state of the distributed storage system, wherein a respective replication request for a respective object instructs a respective instance of the distributed storage system to replicate the respective object so as to at least partially satisfy a replication policy for the respective object, wherein a respective replication policy includes criteria specifying at least storage device types on which replicas of object are to be stored; and distributing at least a subset of the replication requests to the respective instances of the distributed storage system for execution.