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

A method comprising the steps of:

• providing, in a disk drive, at least a first disk surface and at least a first head;
• writing at least a first data pattern of a first data density on the first disk surface using the first head;
• reading the first data pattern from the first disk surface using the first head upon expiration of at least a first predetermined time interval;
• calculating a first thermal decay rate associated with the first data pattern;
• determining whether the first thermal decay rate associated with the first data pattern satisfies a first thermal decay rate requirement;
• and,
• deciding whether to record data on the disk surface at the first data density based upon whether the first thermal decay rate meets the first thermal decay rate requirement.

A method comprising the steps of:

• providing, in a disk drive, at least a first disk surface and at least a first head;
• writing at least a first data pattern of a first data density and a second data pattern of a second data density on the first disk surface using the first head;
• repeatedly reading both the first data pattern and the second data pattern from the first disk surface using the first head upon expiration of predetermined time intervals;
• storing at least a first read value from the first data pattern and a first read value from the second data pattern in memory;
• calculating a first thermal decay rate associated with the first data pattern and a second thermal decay rate associated with the second data pattern using the first read value from the first data pattern and the first read value from the second data pattern, respectively;
• determining whether the first thermal decay rate associated with the first data pattern satisfies a first thermal decay rate requirement;
• determining whether the second thermal decay rate associated with the second data pattern satisfies a second thermal decay rate requirement;
• and,
• selecting a density at which to record data on the disk surface 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.

An apparatus comprising:

• at least one disk surface;
• a head for reading information from and writing information onto the disk surface;
• means for determining a first thermal decay rate of the disk surface at a first data density;
• means for determining a second thermal decay rate of the disk surface at a second data density;
• means for selecting a density at which to record data on the disk surface based upon whether the first thermal decay rate satisfies a first thermal decay rate requirement and whether the second thermal decay rate satisfies a second thermal decay rate requirement.