A plurality of data elements are stored on storage devices in a storage system and are identified by unique identifiers. Each data element has management information associated therewith for enabling management of a quality of service of each data element individually. The management information is individually changeable for each data element for changing the quality of service of each data element individually without affecting the quality of service of others of the data elements. The quality of service of a particular data element can be changed as a result of the storage system receiving a WRITE request sent to the storage system, the WRITE request being directed to a virtual metadata file corresponding to the particular data element and specifying a new quality of service for the particular data element or specifying custom metadata for the particular data element.