1. A computer program product comprising one or more computer readable storage media storing instructions translatable by one or more processors to perform: accessing network file systems at one or more physical locations; collecting file system metadata from the network file systems, wherein the file system metadata comprises one or more pieces of metadata of interest; accessing one or more user defined heuristics, wherein each user define heuristic is an algorithm for deriving a file system statistic associated with a managed object based on the processing of one or more pieces of metadata of interest associated with the managed object, the algorithm and the one or more pieces of metadata of interest are specified by the user and the file system statistic is not file system metadata; applying the one or more user-defined heuristics to the one or more pieces of metadata of interest to generate one or more file system statistics of interest; storing the one or more pieces of metadata of interest and the one or more file system statistics of interest in a metadata repository; enabling a user to define a rule via a user interface, wherein the rule comprises a pattern and an action and wherein the pattern comprise an expression including at least one of the one or more file system statistics of interest; searching metadata records in the metadata repository that match the pattern, wherein determining whether a metadata record matches the pattern comprises evaluating the expression using the at least one of the one or more file statistics of interest associated with the one or more managed objects associated with that metadata record; and applying the action on one or more managed objects in the network file systems that are associated with the metadata records, thereby changing a state of the network file systems wherein file system data is collected at a first time and the file system metadata is collected at a second time and the one or more file system statistics of interest are generated using the file system data collected at the first time and the file system metadata collected at the second time.