Abstract: Systems and methods are disclosed for recording density variation of data tracks. In some embodiments, an apparatus may comprise a circuit configured to record data to a first track of a data zone at a first recording density, and record data to a second track of the data zone at second recording density different from the first recording density. Recording density may be measured as a bits per inch (BPI) value for a data track. Different recording densities may be applied based on a width of the target track. In some embodiments, such as for shingled magnetic recording (SMR), data may be recorded to partially overlapped tracks at a first density, and to non-overlapped tracks at a second density.

Abstract: Apparatus and method for writing data to a data storage medium using shingled magnetic recording (SMR). In accordance with some embodiments, a transducer is positioned adjacent a recording medium. The transducer is used to write data to the medium in the form of partially overlapping tracks grouped together into bands so that a first track and a last track in a selected band are wider than remaining tracks in the selected band.

Abstract: Apparatus and method for writing data to a data storage medium using shingled magnetic recording (SMR). In accordance with some embodiments, a transducer is positioned adjacent a recording medium. The transducer is used to write data to the medium in the form of partially overlapping tracks grouped together into bands so that a first track and a last track in a selected band are wider than remaining tracks in the selected band.

Abstract: Method and apparatus for off-track write error recovery. A storage medium is provided with at least first and second tracks, and a write protected status is assigned to the second track to inhibit subsequent writing of data thereto in relation to a position error detected during writing of data to the first track. Preferably, a third track is disposed between the first and second tracks. The position error is preferably characterized as a first position error, and a write fault condition is declared during the writing of data to the first track in relation to a second position error different from the first position error. Data write operations are preferably performed on additional tracks while the write protected status of the second track is maintained. In this way, dual-sided encroachment or other track squeezing effects are reduced.

Abstract: In a disk drive, a contact write current that causes head-disk contact due to pole tip protrusion is detected using a variance of a position error signal (PES). A method of determining the contact write current includes generating PES's in response to the head reading servo sectors on the disk, calculating PES variances wherein each PES variance is a statistical measure of a different group of the PES's, calculating a change in the PES variances, and selecting the contact write current in response to the change in the PES variances.

Abstract: A predictive failure control circuit and associated method are provided in a data storing and retrieving apparatus. The circuit is configured to schedule a data integrity operation on data associated with a subportion of a data storage space, in relation to a comparison of an accumulated plurality of executed host access commands associated with the subportion. The subportion can comprise a sector or a single track or a band of tracks. A table preferably stores accumulated number of host access commands for each of a plurality of subportions of the data storage space. The data integrity operation can comprise reading the data on to detect degradation and restoring the recovered data to the same or to new, different tracks. The data subportions can also be reallocated to a new location.

Abstract: A preamplifier that includes an input configured to receive a preamplifier control signal and a fault detection circuit configured to monitor the preamplifier control signal received at the input is provided. The fault detection circuit is further configured to identify a fault condition triggered by an improper temperature control signal provided by the preamplifier.

Abstract: A method and apparatus for generating an index location from a spin motor of a disk drive are disclosed. A disk drive includes a motor having a plurality of commutation states, wherein changes in commutation states are controlled by an FCOM signal having FCOM pulses. Ideally, when the motor is spinning at a constant speed, the time between FCOM pulses is constant. However, the inventor of the present invention has recognized that, in practice, the time between FCOM pulses, when measured more closely, is not constant due to mechanical tolerances in the motor. Accordingly, the inventor has determined that the non-constant times between FCOM pulses can be advantageously used to generate a spin motor index in a disk drive. Once obtained, the spin motor index may advantageously be used for a number of purposes.

Abstract: A method and apparatus to control the amount by which thermal expansion causes a write head to extend toward a disk is provided. In one aspect, a single write operation uses two or more different write currents. A first write current is initially used, and is large enough to achieve desired magnetic flux at the disk. After the write current heats and expands the arm tip, and extends it toward the disk surface, the write current is reduced, to avoid or postpone the time at which thermal expansion might cause the tip to contact the disk, or cause other undesirable effects.

Abstract: The present invention provides a method and apparatus for recovering data in a disk drive following a read error. At least a portion of the actuator arm tip is heated. Thermal expansion reduces the read-head-to-disk spacing, increasing the likelihood of success when a re-read of the data is attempted. In one approach, a heater is operatively coupled to the tip. In one aspect, a write head is provided with write current in order to heat the tip. Data which may be modified or overwritten when providing write current to the write head is preferably read and buffered prior to the write operation, for later re-writing to the disk.