a phase change medium , a device and a method for driving a phase change medium are proposed that allow writing at high speed and erasing at low speed . the proposed low - speed erasing option must be seen as a formatting option that can be applied to the whole medium so as to put the medium back to a virgin state . with the invention , direct overwriting of data is not possible : the data have first to be erased at low speed before new data can be written on the medium at high speed . according to the invention , the medium is rotated at a linear velocity that depends on the selected operating mode , the linear velocity applied in the writing mode being much higher than said maximum crystalline velocity , and the linear velocity applied in said erasing mode being equal to or lower than said maximum crystalline velocity . application : dvd + r high - speed .