Method and apparatus for selecting data densities on disk surfaces in a disk drive based upon measured thermal decay rates of the disk surfaces during self-test procedure

The present invention relates to magnetic storage devices and, more particularly, to computer disk drives. More specifically, the present invention relates to determining a data density at which to store data on a disk surface by measuring thermal decay rates for the disk surface for various data densities. A method and apparatus for selecting data densities on disk surfaces in a disk drive based upon measured thermal decay rates of the disk surfaces is disclosed. First and second data patterns having first and second data densities, respectively, are written onto a first disk surface. The first and second data patterns are read, upon expiration of at least a first predetermined time interval, and first and second thermal decay rates associated with the first and second data patterns, respectively, are calculated. A determination is made as to whether the first and second thermal decay rates, respectively, satisfy first and second thermal decay rate requirements. Finally, a density at which to record data on the first disk surface is selected based upon whether the first thermal decay rate meets the first thermal decay rate requirement and whether the second thermal decay rate meets the second thermal decay rate requirement.