1. A method in a data storage system of storing a variable number of instances of data objects, wherein the method is performed by a computing system having a processor and memory, the method comprising: accessing a set of data objects stored in a first set of one or more data stores, wherein the set of data objects includes a plurality of data objects that are substantially similar, wherein the plurality includes a number N data objects; determining, by the computing system, a number X of instances of a first data object of the plurality of data objects that should be stored in a second set of one or more data stores, where X is greater than one and less than N, wherein the intersection of the first and second sets of data stores is empty; determining a number Y of instances of the first data object that are stored in the second set of one or more data stores, where Y is greater than or equal to zero; determining if X is greater than Y; and when X is greater than Y, storing a number Z of instances of the first data object in the second set of one or more data stores, where Z is equal to X minus Y.