1. A method of specifying one or more rules that control the placement of data objects, comprising: determining a system topology of a distributed storage grid; using the system topology to provide configuration options for one or more rules to a user; receiving, for each rule, one or more criteria for comparison with an object metadata value, an object duration value, an object status value, or a value contained in the contents of an object; receiving, for each rule, one or more placement constraints, each placement constraint specifying how an object should be placed within the system topology; creating a data structure that describes the criteria in a form that can be used to compare against objects; creating a data structure that describes the placement constraints in a form that can be used to match against the system topology; incorporating the criteria and placement constraints data structures that comprise the rule with any previously existing rules to form updated rules; distributing the updated rules across the system; triggering the processing any existing objects that are affected by the addition of new rules or modification of existing rules.