Dynamic variable capacity hard disk drive

A disk drive includes an environmental monitor, a controller and a writing mechanism. The controller acts in response to an output from the environmental monitor to determine if the data capacity of a disk drive could be increased from a first value to a second value. The controller determines the second increased value. The writing mechanism, controlled by the controller, writes data to the disk to realize the increased data capacity of the disk drive. A method for increasing the data capacity of a disk drive from the factory settings for data capacity includes determining if the disk drive is in a favorable or stable environment, writing data to at least one portion of the disk drive at a higher capacity than the factory setting for the at least one portion of the disk drive, and resetting the capacity for at least one portion of the disk drive.