Abstract: A method of evaluating a condition of a head-disk interface (HDI) of an operational disk drive. The disk drive includes at least one disk having a disk surface and at least one transducer head for writing and/or reading data from the disk surface. In this regard, the transducer head is sensitive to temperature changes. With this in mind, the method includes rotating the disk at an operational rate. A first thermal signal is received from the transducer head that is indicative of thermal activity at the transducer head. The first thermal signal is analyzed for thermal transients. Based upon this analysis, first thermal variation information indicative of a relationship of thermal transients in the first thermal signal relative to a baseline is generated. Finally, the first thermal variation information is compared to threshold information indicative of an acceptable HDI. In one preferred embodiment, a prediction of an impending head crash is made based upon the comparison.

Abstract: A magnetic recording and/or reproducing apparatus which achieves high performance encoding and high efficiency decoding to lower the decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes, in its recording system, an error correction coder 51 for error correction coding input data and an interleaver 52 for scrambling the sequence of data supplied from the error correction coder 51.

Abstract: A transducer position sensing system in a disc drive to take frequent data measurements from micro-servo sectors on the disc and to interpret the information to predict recording failures. The disc drive is formatted with many small or micro-servo sectors containing, among other things, a servo address mark, encoded disc location information, and radial track position information. The sensing system frequently retrieves this information through the transducer, compares the measurements to expected values, and given unexpected measurements predicts errors. The time elapsed between the passing of servo address marks can be used to predict adjacent sector overwrites. The radial track position information can be used to predict off-track write errors. The radial track position signal amplitude can be used to predict the transducer moving too far from the disc, resulting in skip write errors.

Abstract: Method and apparatus for increasing process yields of data storage devices which store data on media surfaces using read/write heads. An initial linear bit recording density is determined for each head, the linear bit recording density comprising a density at which each head is capable of writing data to and reading data from the corresponding media surface. Defective storage sectors are identified on the media surfaces to determine whether a sufficient number of logical storage sectors are available to meet a predetermined data storage capacity. The linear bit recording density of at least one of the heads is then altered to ensure that the storage device has sufficient logical storage sectors to meet the predetermined capacity.

Abstract: The present invention is a method and system to determine a quality of a head in a hard disk drive. The method comprises providing a disk having a at least one side with a plurality of tracks, writing on a predetermined track on the plurality of tracks and reading a profile of the predetermined track to provide a first profile value. The head is then moved to an adjacent track where it writes on the adjacent track. A profile of the predetermined track is then read to provide a second profile value. A quality of the head can then be determined based on the first and second values.

Abstract: A method and apparatus for Viterbi detector state metric re-normalization. The method includes fabricating a Viterbi detector (138) having a predetermined number of states, wherein the Viterbi detector (138) stores a state metric value and a branch metric value for each state, and wherein the Viterbi detector (138) implements a trellis diagram. The method includes constructing a Viterbi detector (138) which can support a state metric value having g+h′ number of bits. The number of bits needed to represent the branch metric value is represented by (g) and the additional number of bits needed to represent the state metric value is represented by (h′). The additional number of bits (h′) is less than the additional number of bits (h) determined using the following inequality: 2h−1−h≧K−1, wherein K represent the constraint length of the trellis diagram.

Abstract: A method of alternate tape repositioning during data recovery which takes advantage of the reverse half of the tape forward/reverse cycle to perform an error recovery procedure invoking, thereby reducing total data recovery time. In the event that a tape drive fails to read a target data block, the tape continues its linear travel until a forward ramp-up point beyond the target data block is reached. The tape drive changes tape travel direction to a reverse linear travel direction. When the tape heads are on top of the target data block, a first error recovery procedure invoking is performed in the reverse linear travel direction. If the first error recovery procedure invoking fails to recover data, tape continues its reverse linear travel until a reverse ramp-up point past the target data block is reached. Once again, the tape drive changes tape linear travel direction and a second error recovery procedure invoking is executed in the forward linear travel direction.

Abstract: Written-in runout due to vibration of the cage of a spindle motor of a disc drive is detected by identifying an initial cage frequency value of the motor. A written-in magnitude of successive servo burst closures, D(nc), is read over a plurality of tracks, and a maximum servo burst closure D(ncp) is identified from the plurality of read servo bursts. A magnitude of the cage frequency at a servo sector n0 is calculated based on a difference between the read magnitudes of the servo burst closures at servo sectors nc and nc+1, and a phase of the cage frequency is calculated based on the magnitude of the written-in cage frequency at servo sector n0. The profile, in the form of cage frequency, maximum servo burst closure magnitude, and initial phase, is stored in a memory or table for each of a plurality of radial zones of tracks. The profile is combined with a position error signal and applied to the controller in a feed forward scheme to adjust the position of the head based on the written-in runout.

Abstract: A method and system are described for preventing data loss from an off-track write condition in a disk drive. In accordance with exemplary embodiments of the present invention, the disk drive comprises a disk surface comprising a first track and a second track adjacent to the first track, and a head for writing data to and reading data from the first and second tracks. The method of recovering from the off-track write condition comprises the steps of receiving a write command to write a first series of data blocks on the first track. Before writing the first series of data blocks, a second series of data blocks stored in the second track is read and stored in a data buffer.

Abstract: A magnetic recording medium for recording information by forming a magnetic pattern for information thereon by a magnetic head, which is a longitudinal magnetic recording medium having a coercive force of at least 3000 Oe, and which has a magnetic pattern for control of the magnetic head preliminarily formed thereon, wherein the full width at half maximum of an isolated pulse of a reproducing signal of the magnetic pattern for control is smaller than the full width at half maximum of an isolated pulse of a reproducing signal of the magnetic pattern for information.

Abstract: A high-level region and a low-level region are formed on a surface of a nonmagnetic base member, in which high-level region is formed a ferromagnetic thin film pattern which corresponds to a preformat information signal, in such a structure that a flow promoting shape of such a shape (e.g., smooth curved shape, polygonal shape) that inhibits the stagnation of a flow of a detergent to promote the flow in order to prevents sticking and residing of foreign matter contained in the detergent is formed at an area where the detergent is liable to stagnate in the high-level region, i.e. at an inner radial portion of a disk-shaped mater information carrier.

Abstract: A recording disk contains at least two types of servo sector format, including a first type having a relatively larger track identifying field containing the track number, and a second type having an abbreviated track identifying field identifying a track within a range of tracks, the range being less than the full range of tracks on the disk surface. Preferably, Gray code encodings are used, the first type of track field contains sufficient Gray code bits to identify the ful track number, every Nth servo sector is of the first type, and all servo sectors in between are of the second type, N being at least 2. As a result, the disk area required for track identification is reduced, and the additional disk space available can be used to expand the PES field.

Abstract: An apparatus and method of predicting functional capability of a data storage device having a plurality of information tracks, comprising performing a DC erase on three adjacent information tracks, writing a predetermined bit pattern on a middle track of the three adjacent information tracks, providing a first signal from the bit pattern to a variable gain amplifier to generate a first value of the variable gain amplifier, performing DC erases on the information tracks adjacent the middle track, reading the bit pattern from the middle track to provide a second signal to the variable gain amplifier to generate a second value of the variable gain amplifier, and operating on the first and second values of the variable gain amplifier to provide a track mis-registration value for use with a predetermined threshold value to determine the functional capability of the data storage device.

Abstract: Embodiments of a data storage tape control system are disclosed that works to prevent or reduce frequency of off-track errors. The invented method slows tape speed in response to the writing head or writing element moving transversely away from a track center a predetermined distance, called an “off-center limit,” wherein the off-center limit is part of the way to an off-track error limit. The off-center limit is close enough to the center of the track that the writing operation is still effective, but wherein further movement out from the center would result in an off-track error and possible overwriting or unreadable data. The tape speed reduction is preferably done in increments until the writing head/element is closer to the center of the track than the off-center limit. Speed reduction is preferably done concurrently with writing, so that writing is not interrupted.

Abstract: A recording surface is segmented into a plurality of radial zones each containing a plurality of concentric tracks on which data may be recorded. The recording surface is initially formatted with a data frequency for each zone such that all of the zones have substantially the same data density. The data frequency is reduced for a first zone whose error rate is initially less than the predetermined error rate so that the first zone exhibits an error rate meeting the predetermined error rate. The data frequency for a second zone whose data transfer error factor initially exceeds the predetermined error rate is increased to restore any loss of storage capacity of the recording surface due to the reduced data frequency in the first zone. As a result, the data density in the first zone is substantially less than a nominal data density and the data density in a second zone is substantially greater than the nominal data density.

Abstract: The present invention provides a novel method and apparatus for decoding digital information transmitted through the communication channel or recorded on a recording medium. The method and apparatus are preferably applied in the systems where data is encoded using regular LDPC codes with parity check matrices composed from circulants (a matrix is called a circulant if all its column or row are cyclic shifts each other).

Abstract: The invention relates to control systems for data storage media. More particularly, the invention relates to a system, method and apparatus for forming various frequency modulation patterns on storage media for providing position error signals. The invention also relates to forming various frequency modulation patterns on storage media for providing position error signals having a continuously varying frequency that is proportional to the position of a read/write transducer head within a track defined on a storage medium. The invention also relates to providing a demodulated signal that is proportional to a continuously varying position error signal frequency and thus to the position of the read/write head within a track defined on a storage medium.

Abstract: The present invention relates to a method of enhancing a preamplifier read recovery in a hard disk drive system and comprises the steps of determining whether the hard disk drive system is transitioning from a non-read state to a read state and initiating a non-read state to a read state transition sequence when a transition from the non-read state to the read state is determined. The transition sequence is independent of a type of non-read state prior to the transitioning. After the non-read state to read state transition sequence is complete the read mode is initiated. In addition, the invention comprises a system for controlling a transition from a non-read state to a read state associated with a preamplifier in a hard disk drive system.

Abstract: The present invention relates to a data write control system for writing data onto a disk in response to a write request. Before the data is written onto a disk in a floppy disk drive (17), a FD driver (120) stores the data in a predetermined area of a main memory (12). Note that the data involves a probability of being unsuccessfully written onto the disk. After the data has been written on the disk, the FD driver (120) reads out the written data from the disk, and compares the read-out data with the data stored in the predetermined area so as to determine whether or not the data written onto the disk has been successfully written.

Abstract: A method, apparatus and computer program product are provided for head crash predictive failure analysis based upon slider track misregistration measurement using the readback signal. A transducer head is selected. Then the transducer head is positioned off-track. A readback signal is obtained from the transducer head positioned off-track. The readback signal is processed and compared with historical values to identify head disk interference. The processing of the readback signal includes amplifying the readback signal using arm electronics. The amplified readback signal is demodulated to provide a demodulated signal that is proportional to its amplitude. The demodulated signal is bandpass filtered using a bandpass filter having a selected center frequency for the selected transducer head.