1. A computer-implemented method for simulating a state of a distributed storage system having a plurality of instances, 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: obtaining a current state of a distributed storage system and replication policies for the objects in the distributed storage system, wherein a respective replication policy for a respective object specifies parameters for allocating copies of the respective object among the plurality of instances; receiving proposed modifications to the current state of the distributed storage system; simulating the state of the distributed storage system over time based on the current state of the distributed storage system, the replication policies for the objects in the distributed storage system, and the proposed modifications to the current state of the distributed storage system; and generating reports relating to the time evolution of the current state of the distributed storage system based on the simulation; wherein a respective proposed modification to the current state of the distributed storage system includes information relating to the respective proposed modification to the current state of the distributed storage system and a time at which the respective proposed modification to the current state of the distributed storage system is to occur.