Abstract: The misplacement of a servo burst during a servowriting or self-servowriting process can be corrected by erasing and re-writing that burst. A servo pattern can be selected that has sufficient radial separation between bursts such that if a burst is re-written and trimmed there should be no damage to adjacent bursts. The radial separation can be selected to be greater than the width of the appropriate write element in order to allow for some misplacement of the element during the erasing and/or re-writing of the misplaced burst. Alternatively, a batch writing approach can be used to minimize the time needed to re-write misplaced bursts. In addition, WORF information of a track can be saved in memory for future servowriting and/or can be utilized to calculate a threshold for identifying servo bursts to be repaired. This description is not intended to be a complete description of, or limit the scope of, the invention.

Abstract: The operation of propagation self servowrite can be improved by using spirals written upon the disk. The spirals can be used to reduce the DC drift of the propagation of the self servowrite. The writing of the spirals can be improved by using the back EMF signal for the VCM to control the velocity of the actuator during the writing of the spirals to produce a more consistent spiral shape. Additionally, back EMF crossings of the spindle can be used to space the spirals evenly about the disk.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. Additional bursts can also be written, such as for each data track centerline. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: To account for head misplacement while servowriting, conditional writing and/or trimming of servo information can be used. Conditional servowriting allows servowriting to be disabled when it is determined that servo information will not be written and/or trimmed at a desired location or within a threshold distance of a desired location. For example, if a distance between a write element or a predicted location of servo information and a desired location of the servo information or write element exceeds a threshold, writing and/or trimming can be inhibited. Servowriting can be resumed when it is determined that servo information will be written or trimmed at a desired location or within a threshold distance of a desired location. A servowriting step or pass is not re-started when the threshold is exceeded and those wedges for which servo information was not written and/or trimmed can be attempted during subsequent revolutions of the rotatable storage medium.

Abstract: Systems and data storage devices in accordance with embodiments of the present invention can execute instructions to determine a width of a data stroke along a rotatable medium. In one embodiment, the width can be determined by measuring a distance from a marker zone edge of a template pattern on the rotatable medium to a ramp positioned adjacent to the rotatable medium or near the inner diameter of the rotatable medium, and measuring a distance from the marker zone edge to a crash stop. A track layout can be determined based on the width of the data stroke.

Abstract: Reference patterns in accordance with the present invention can include variable frequency chevrons incorporated into a reference pattern on a printed media surface to improve servo demodulation. In an embodiment, the reference pattern can include one or more servo wedges having a preamble including digital information at a first frequency relative to the head when the rotatable medium is rotated at a spin speed. The servo wedges further include at least one field having a first set of a plurality of phase-bursts forming a positive chevron angle relative to the preamble and a second set of a plurality of phase-bursts forming a negative chevron angle relative to the preamble, wherein a frequency of the at least one field relative to the head when the rotatable medium is rotated at the spin speed varies between a first end of the media surface and a second end.

Abstract: A two-step self-servowriting process first writes an intermediate pattern based on a reference pattern, and then writes a final pattern based on the intermediate pattern, wherein the reference pattern can be a printed media or a spiral pattern. Such an approach can be utilized to reduce the noise/runout, eliminate timing eccentricity, and increase the sample rate of the final pattern. In addition, a disk drive containing multiple rotatable disks can perform two-step self servowriting using either a per-cylinder process to further improve written-in runout. In such a process, intermediate servo patterns can be written via each head in the drive, and the final servo patterns can be written and/or re-written via each head at one time based on an optimal intermediate pattern. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions of the media will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. Additional bursts can also be written, such as for each data track centerline. The overall error in position should decrease as the number of passes used to write a burst pair increases. Also, additional bursts can be written in separate passes in order to further reduce position error while avoiding coherence concerns.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where servo bursts are used to define a position on the media, trimming a first burst and writing a second burst on separate revolutions of the media will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a combination of bursts, each burst also can be trimmed and/or written in multiple passes. The overall error in position should decrease as the number of passes used to write a burst combination increases. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: Methods are provided for selecting write elements, that can be used in a media-writer, for writing servo burst patterns that have a desired width. Methods for writing preferred servo patterns are also provided. Methods for controlling a write current to produce servo bursts have a desired width are also provided. In accordance with specific embodiments of the present invention, the desired burst width is three-fourths of a data track wide. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures and the claims.

Abstract: Systems for writing preferred servo patterns, and rotatable storage media including preferred servo patterns, are provided. Systems for controlling write currents to produce servo bursts having a desired width are also provided. In accordance with specific embodiments, the desired burst width is three-fourths of a data track wide. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures and the claims.

Abstract: A hard drive retrieves critical data determined to be requested by a host device in the near future and stores it in cache. The hard drive provides the critical data to the requesting host upon receiving the request, thereby eliminating the time required to respond to the request due to media accessing. The critical data is retrieved upon the occurrence of a critical event. The critical data may be related to power-on of the computer, such as boot sector FAT system data. Thus, the cache of the present invention may use old data rather than new data or the last data accessed.

Abstract: A disk drive system includes an adjustable output (linear or switching) voltage regulator including an output terminal that provides an output voltage. A plurality of loads each include a voltage supply terminal that receives the output voltage. A controller dynamically adjusts the output voltage based, e.g., based on which of the loads are active.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: A method for determining embedded runout correction (ERC) values using iteration and variable gain in a disk drive. A disk has a track written thereon, an ERC value is determined for a servo sector on the track using variable gain, and the variable gain decreases based on the number of revolutions of the disk.

Abstract: In order to account for the misplacement of a write element during a servowriting process, the width of the information being written can be varied. In a self-servowriting disk drive, for example, the write current supplied to a read/write head can be adjusted to vary the width of information, such as servo bursts, written by the head. By calibrating the head and determining the misplacement of the head while writing, an edge of a servo burst can be placed in the desired position regardless of the misplacement of the head simply by adjusting the width of the written burst. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: To account for head misplacement while servowriting, adjustments to thresholds used during writing and/or trimming of servo information can be used. A threshold can be used to disable servowriting when it is determined that servo information will not be written and/or trimmed at a desired location or within a threshold distance of a desired location. In multiple pass servowriting, a threshold can be adjusted for a pass or step or portion thereof using a position-error during a corresponding operation. For example, the position-error while trimming a first servo burst can be determined. Using the position-error, the threshold can be adjusted. The adjusted threshold can be used while writing a corresponding second servo burst. The threshold can be increased in a direction opposite to the determined position-error and decreased in the direction of the determined position-error. In this manner, the probability that the two bursts will identify a desired location can be increased.

Abstract: A two-step self-servowriting process first writes an intermediate pattern based on a reference pattern, and then writes a final pattern based on the intermediate pattern, wherein the reference pattern can be a printed media or a spiral pattern. Such an approach can be utilized to reduce the noise/runout, eliminate timing eccentricity, and increase the sample rate of the final pattern. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.