Modifications made to files (e.g., stub files) within a distributed file storage system over a defined time period are determined. Moreover, the distributed file storage system employs a tiered cloud storage architecture. In one aspect, snapshots of a stub file can be generated at different instances of time. Further, metadata of the stub file within the different snapshots can be compared to determine whether the stub file has been modified. As an example, the metadata can include cache metadata that describes the content within the cache of the stub file and/or mapping metadata that describes the content within cloud storage that is referenced by the stub file.