Method, system, and computer program product embodiments of controlling filling levels of a plurality of storage pools are provided. A plurality of files is selected from each storage pool of the plurality of storage pools. Each file is then copied to a server and a list is updated. The list comprises an entry for each file of the plurality of files. Each entry comprises a status information. The status information indicates that the corresponding file has been copied to the server. Each entry further comprises an identifier indicating the storage pool on which the corresponding file is stored. If it is detected that the filling level of a storage pool reaches a predefined first threshold value, then a first set of files is determined by use of the list. Each file of the first set of files is replaced by a stub file. The status information is updated.