1. At least one tangible computer-readable data storage storing instructions for controlling at least one data processing system to identify data files complying with a query for certain data files, comprising: receiving a query for data files, wherein the query relates to satisfying a compliance criteria; based on the received query, searching at least one metabase to locate metadata describing data files satisfying the compliance criteria, wherein the metabase is a database comprising metadata associated with the data files, wherein the metadata includes data classifications that describe characteristics of the data files, and wherein the metadata is not stored with the data files; and, providing responding data, wherein the responding data relates to data files satisfying the compliance criteria based on the located metadata, and wherein the responding data identifies both primary and secondary storage locations associated with at least some of the data files satisfying the compliance criteria.