Systems, methods, and computer readable storage mediums for discovering volumes which are good candidates for space reclamation. A storage subsystem identifies the file system storage capacity for a given volume from the file system metadata of the given volume. Then, the storage subsystem compares the file system capacity of the given volume to the allocated capacity on the storage subsystem. If the allocated capacity is greater than the file system capacity by a given threshold, the storage subsystem marks the given volume as a candidate for space reclamation and generates an alert to the user to reclaim the space of the given volume.