One embodiment is a method and apparatus for modifying retention periods in a storage system, in which previously defined retention periods for units of data may be reduced. In another embodiment, the retention period of a unit of data may be modified in response to the occurrence of an event by renewing previously defined retention periods until the occurrence of the event is detected. If the occurrence of the event is detected, a retention period associated with that event may be established for the unit of data. In yet another embodiment, retention classes are used to define retention periods for units of data so that the retention period of a unit of data may be modified without modifying the unit of data itself. In a further embodiment, a request to the storage system to reduce a retention period includes authentication information that the storage system may use to verify the request.