A storage system is proposed which comprises a data storage device including a number N of removable storage media for storing data, with N≧2, and a number m of drives, with m≧1, wherein each of the m drives is configured to drive one of the removable storage media mounted to the drive. The storage system includes a server being coupled to the data storage device and configured to serve requests from clients, and a controller which is configured to control the data storage device to adaptively unmount the removable storage media based on a monitoring information of the requests at the data storage device, states of the drives, and states of the removable storage media.