Abstract: A recording system stores recording cycle information identifying the parameters for recording user data on a particular data sector. During a subsequent operation, the recording system employs the recording cycle information to select a different set of parameters for recording new user data at the particular data sector. One of the parameters might identify a recorded pattern in a balance pad at the data sector, and another one of the parameters might identify a scrambler seed value. By employing a different set of recording parameters for each occurrence of recording user data at the particular sector, sample timing of, for example, a read channel might be based on an average of easy and hard transitions.

Abstract: A type of servo pattern suitable for tracking systems in magnetic recording devices such as floppy disks or linear tape or hard disks or in other machines. The pattern comprises several phase-encoded elements that provide an absolute transverse position coordinate from local data. Computations can be made with channel chips commonly used in magnetic recording disk drives.

Abstract: A signal separation circuit (11) normally outputs a main signal, but outputs a TMCC signal when an error detection and correction unit (4) sets a completion flag. Main signals are input via a selection circuit (3) to an execution unit (4), where error correction of the main signals is performed. The error-corrected main signals are supplied via a switching circuit (8) to a first data output circuit (9). Meanwhile, TMCC signals are input via the selection circuit (3) to an execution unit (4), error correction is carried out to the TMCC signals. The error-corrected TMCC signals are supplied via switching circuit (8) to a second data output circuit (10).

Abstract: A device comprises a memory array in which a plurality of codewords is stored. Each codeword comprises an error correction code and a data block that comprises a plurality of units of data. The device further comprises an error code correction module coupled to the memory array. When multiple units of data are to be read from the device for an address, a codeword stored in a location associated with the address is fetched from the memory array, the error code correction module decodes the codeword and corrects any errors in the data block for that codeword, and the multiple units of data are read from the corrected data block.

Abstract: A magnetic recording system having a magnetic-recording medium with data sectors wherein a preamble pattern of a prescribed cycle is recorded, the preamble pattern having the cycle of a predetermined T, wherein T represents a minimum duration of a data-recorded bits in the data sectors. The system includes a magnetic head to reproduce the preamble pattern and a signal-processing circuit to process data to be recorded in and reproduced from the data sectors. The signal-processing circuit including (i) a sampler for sampling a signal reproduced from the preamble pattern and (ii) a corrector for correcting the amplitude by using maximum and minimum amplitude values in each cycle of the preamble pattern sampled by the sampler.

Abstract: The present invention differentiates between systematic and non-systematic conditions by observing a figure of merit over a series of many observation events. In a data storage recording environment, the particular figure of merit used is the number of data segments that must be re-written (due to errors) to a recording medium in order to assure that an entire data set is correctly written. A larger number of re-written segments is indicative of a significant error condition. After each data set is completely and correctly written, the number of re-written segments for the data set is reported as an “event.” A running history of the classified events (or the events themselves) is maintained. Then, at a predetermined time, the history is analyzed and a decision made as to whether any observed events meets predetermined criteria for a systematic condition.

Abstract: Disclosed are techniques related to cluster-based defect detection testing for disk drives. A disk drive comprises a disk, a moveable head to scan the tracks of the disk, and a defect detection circuit to detect defects on the disk scanned by the moveable head. The disk drive includes a microprocessor for controlling operations in the disk drive including cluster-based defect detection. The microprocessor under the control of a cluster detection program defines a scan window. The scan window corresponds to an area of the disk scanned by the moveable head. The microprocessor under the control of the cluster detection program further defines a cluster threshold corresponding to a minimum number of defects required to occur within the scan window and identifies a defect cluster if a cluster threshold of defects occurs within the scan window. By identifying defect clusters on the disk these defect clusters can be margined.

Abstract: The present invention may be regarded as a disk drive comprising a disk having a plurality tracks, each track comprising a plurality of data sectors. If an error occurs while attempting to read one of the data sectors, a retry operation is executed in an attempt to recover the errant data sector. Averaged read data is generated over multiple retry operations, and the averaged read data processed to recover the errant data sector. In one embodiment, the averaged read data comprises an averaged binary sequence detected over multiple retry operations. In another embodiment, the averaged read data comprises averaged read signal sample values generated over multiple retry operations.

Abstract: A disk device performs position control of a head. An acquiring unit acquires correction information and check information from a disk for checking the correction information. A judging unit judges whether the correction information acquired should be used for correcting position information recorded in the disk, based on the correction information acquired and the check information acquired.

Abstract: A system to ensure written data integrity in a data storage device that is operating outside of predefined normal operating conditions is disclosed. The system includes an environmental stress monitoring module operable to identify data storage device operation in an environmental stress condition and a write integrity check module for verifying written data integrity during data storage device operation in the environmental stress condition. The system and method of data protection provides a means of ensuring written data integrity without sacrificing performance during normal drive operational environmental conditions.

Abstract: The present invention is an apparatus and method for protecting against drive anomaly errors while optimizing random read performance. Data block persistency is explicitly verified when a data block is written. Data block integrity and location checks are performed by reading data from a single drive. Through such a process, reading of metadata from a second drive is not required, thus decreasing the drive I/O workload. In an example of the invention, a combination of a CRC and a location tag interleaved as metadata along with user data on a single drive may be employed to perform a read operation in accordance with the present invention.

Abstract: A planar servo verifier head is provided comprising a plurality of magnetic head elements optimized for the readback process. The plurality of magnetic head elements are fabricated in a planar two-dimensional array in which individual elements can be used to read servo format tracks spaced across the width of a magnetic tape. In one embodiment, the magnetic head element comprises a read transducer formed of one or more turns of a sense wire inductively coupled to a magnetic yoke in a trench formed on the transducing surface of a substrate. In another embodiment, the magnetic head element comprises a read transducer formed of a thin film magnetoresistive sensor coupled to a magnetic flux guide in a trench formed on the transducing surface of a substrate. According to the method for manufacturing an embodiment of the servo verifier read head for magnetic tape recording, a plurality of trenches are formed in a nonmagnetic substrate wafer, preferably, a ceramic wafer.

Abstract: A method of and an apparatus for controlling a data storage system according to a temperature which thermally expands a write head pole tip of a write head includes supplying the write head with a predetermined warming current in a low temperature environment, so as to prevent a degradation of a writing characteristic of a signal in an initial writing stage. Therefore, errors due to a degradation of a signal level written in a sector of an initial writing mode do not occur by performing a warming write using the predetermined warming current so that data existing in a storage system before performing a writing mode is not erased, and by sufficiently thermally expanding the write head pole tip of the write head until a saturation state before writing starts.

Abstract: A magnetic disk drive improved in reliability of data retrieve. This invention prevents the drive from decoding already-written old data. The failure decoding is caused by a deviation in a write operation, by a malfunction of a writing head and so on. When data in a sector is renewed, the sector's location and renewal frequency information are saved not only in the sector of the disk media but also in a temporary memory. When the magnetic disk drive is in an idle mode, those renewal information written in the sector and stored in the temporary memory, are checked. If both renewal information match, the data is regarded “not old” and the information about the sector in the temporary memory is deleted. In the deleting operation, check mark information indicating that the written data has been checked is written in the sector of the magnetic disk medium.

Abstract: A method for determining a type of a head in a hard disc drive, the head being a normal head, a weak head, or an ATE (Adjacent Track Erasure) head, and a method for adjusting a write parameter using the head type determining method. The head type determining method includes writing data via the head under multiple tracks per inch (TPI) conditions, in which TPIs are equal to a reference TPI, and wider and narrower than the reference TPI by a respective first and second predetermined ratios, and reproducing the written data, to detect a bit error rate under each TPI condition, and comparing the bit error rate under each condition to the bit error rate of the reference TPI, to determine a type of a head.

Abstract: A method for determining an adjacency relation for analyzing a business card containing data blocks. A target data block and a comparison data block is selected from the data blocks. Then, the method checks whether the comparison data block is topologically overlapped with the target data block. If they are topologically overlapped, then it checks whether the comparison data block has the shortest distance to the target data block, in comparison with data blocks that are topologically overlapped with the target data block. If the distance is shortest, then it checks whether there exists an interrupted data block between the comparison data block and the target data block. If there exists no interrupted data block, it is determined that there exists an adjacency relation between the comparison data block and the target data block. A computer readable recording medium is also disclosed, which executes the method as mentioned above.

Abstract: A method optimizing a recording current in consideration of operating temperatures of a hard disk drive and a method of setting a recording density in consideration of tracks per inch (TPI) or adjacent track erasure (ATE) characteristics. The method of optimizing the recording current measures a rate of errors under a test condition corresponding to the operating temperature of a hard disk drive, while changing a recording parameter, selects a recording parameter value corresponding to a smallest rate of errors, and optimizes the recording current for the hard disk drive under operating environmental conditions using the selected recording parameter value.

Abstract: A N-level cell memory controlled by the memory controller of the invention have an internal configuration in which the plurality of data input/output terminals connected to the second data bus are separated into first through Mth data input/output terminal groups, such that there is no redundancy in the n bits of data associated with one N-level cell. Together with this, the memory controller separates the plurality of data bits on the first data bus into first through Mth data groups, the ECC circuits generate error-correction codes for each of these data groups, and the first through Mth data groups and first through Mth error correction codes are input to the first through Mth data input/output terminals of the N-level cell memory, via the second data bus.

Abstract: An off-track retry method for recovering data incorrectly read due to a read error caused by an off-track error in a disk drive. The off-track retry method includes extracting read gain characteristics while varying an off-track amount, determining an off-track amount, i.e., off-track direction and degree, based upon the read gain characteristics, reading data using the determined off-track amount, and determining whether the read data is normal and determining whether the data incorrectly read due to the read error has been recovered based upon the result.

Abstract: A magnetic disk apparatus and a servo pattern recording method therefor, enabling writing of servo signal with high quality, without being affected with ill influences due to fluctuation on a rotation speed when conducting the self servo write operation, comprises: a magnetic disk 102; a head 103 having a write element for use of recording information onto the magnetic disk and a read element for reproducing information from the magnetic disk; and an actuator for moving said head to a desired radial position on the magnetic disk, wherein on the magnetic disk is recorded servo patterns 110 for positioning the head on a recording surface thereof, and within each of the servo patterns are recorded, a pattern sector marker 208a as a marker for detecting passage time of the head, a track ID code 209, and a burst pattern 210 for use of detection of the radial position of the head, following a preamble 207a for use of synchronization of time-base circuit, and further recorded and disposed a second preamble 207b and

Abstract: A storage apparatus for sequentially writing a plurality of blocks of data generated by dividing data on a data recording medium, the storage apparatus including: a sequential writing unit for sequentially associating and writing each of the plurality of blocks with validity information indicating whether or not data contained in the block is valid, on the data recording medium; an error detecting unit for detecting that writing of a single block causes the validity information of the single block to be written in an error area that generates a write error on the data recording medium; a write-area changing unit for changing a write-area in which an additional block is written to cause the additional block written before the single block, excluding the validity information of the additional block, to be written in the error area and the validity information of the additional information to be written in an area other than the error area; and an error circumventing unit for writing the single block in a write-

Abstract: Embodiments of the present invention relate to detecting a flying high state in which a head/slider is flying stably at a high flying position, and then to restore the head/slider to a normal flying position. The detection is made by detecting a read output of a head using a head output detector, and by detecting a gain of a VGA using a gain detector. A control unit uses a value measured in a normal flying state as a reference value to compare a detected value with the reference value. If the compared values differ from each other, the control unit judges that a flying high state has occurred. The control unit, therefore, moves the head/slider to the vicinity of the innermost circumferential track of the disk, or unloads the head/slider.

Abstract: The invention presents techniques for verifying patterns, such as time-based servo marks, recorded on magnetic media. Patterns of this kind can be recorded on a magnetic medium using a recording head that includes a surface having a flux gap with a defined shape. The patterns may be verified with a verify head, having a surface with a flux gap with the defined shape or part of the defined shape. The verify head may include two or more ferromagnetic cores, with a flux gap associated with each core. Each core can independently verify part of the recorded pattern.

Abstract: A method for identifying defective data sectors in a disk drive comprising generating a test pattern on a portion of a disk surface; reading the test pattern on the portion to detect an error and if an error is detected: associating the error with a physical location on the portion to identify a defective area unsuitable for user data; and assigning a severity category to the defective area. The method further comprises providing a physical defect list (P-list) for listing each defective area, the P-list having a predetermined limit to restrict a number of P-list entries; and posting the defective areas having a first severity category to the P-list and if the P-list limit is not exceeded by the first severity category entries: posting defective areas having a second severity category to the P-list.

Abstract: In a method for generating a confidence level of a position error signal (PES) component that is indicative of a quality of the PES component, a PES component is generated using position signal samples of a read back signal corresponding to a servo burst pattern. Next, a noise level corresponding to noise in the read back signal is extracted using the position signal samples. A confidence level is then generated based on the PES component and the noise level. A system for performing the method includes a transformation block, a position error signal (PES) component extractor, a noise extractor, and a confidence level generator. The transformation block is configured to receive position signal samples of a read back signal corresponding to a servo burst pattern taken at a sampling frequency. A transformed domain representation of the position signal samples is then generated by the transformation block based on the sampling frequency and the servo burst pattern.

Abstract: A recording target error rate is selected for one or more of data storage devices, and for each data storage device, a dither value is determined for each read/write head in the data storage device, wherein for each head, using a dither value for writing data, essentially provides the selected recording target error for all the heads.

Abstract: A data recorder for recording data on a recording medium includes a data storage part, an error detection part, an erasure part, a determination part, and a recovery part. When the error detection part detects a data transfer error, the determination part determines whether data corresponding to the data erased by the erasure part is stored in the data storage part. When the determination part determines that the corresponding data is stored in the data storage part, a recovery part recovers the erased data on the recording medium based on the stored data.

Abstract: The present invention includes techniques for programming and verifying data in a programmable circuit. Programmable circuits such as PLDs may include a plurality of rows and columns of memory cells. Data is programmed into memory elements associated with the rows and columns. Subsequently, the programmed data may be extracted for verification. A first word line may be selected by first word line address bits in row shift registers. Data programmed into the first word line is loaded into column shift registers for verification during one or more verify steps. During a program step, data is programmed into memory elements in a second word line that is selected by the first word line address bits. The present invention also provides a technique for shifting program data bits into the column shift registers at the same time that verify data bits are shifted out of the column shift registers.

Abstract: The invention provides a read-while-write recording system for a linear data storage medium, such as magnetic tape or other data storage medium in which data is stored on parallel data tracks that extend along a length of the medium. The invention makes use of separate sliders for the read and write elements, and separate actuators to control the positioning of the sliders. Each of the sliders may also include servo elements to read servo marks. In order to limit the effect of movement of the first slider on the positioning of the second slider, a tape guide is implemented between the different sliders.

Abstract: A disk drive is disclosed wherein if multiple retries beyond a threshold are required to recover a data sector during a normal read operation, the data sector is added to a marginal sector list. During an off-line scan, the data sectors in the marginal sector list are verified. If the verification of a data sector fails, the data sector is relocated.

Abstract: The present invention provides a data recording method a data recording and/or reproducing apparatus for recording data transmitted from a computer to a magnetic tape. In case a recording head fails to write data (data ID=582) of fragment ID=5 to a track (track 7), then, the data is rewritten to the first fragment (ID=0) of a next track (track 8). Thus, the data can be rewritten not on the track basis but on the fragment basis, which can reduce loss of tape capacity significantly.

Abstract: A disk drive has timing marks (TMs) on the disk, that are chosen to reduce the probability of misidentification of a TM in the presence of read errors. The disk drive searches for TMs within a fixed TM search window which extends past the TM on the disk. A TM preferably maximizes the post-shift sliding distance for m post-shifts of the TM pattern, where m corresponds to the TM search window boundary. In this manner, the probability of a misidentification of the TM due to a post-shift having a small distance from the TM pattern is reduced. The TM pattern also provides pre-shift error resistance.

Abstract: A method and system for providing programmable self-testing of a data storage device comprises selecting one or more host programmable tests stored in memory in the data storage device by setting data in a first log in memory of the data storage device. Parameters for execution of the one or more host programmable tests are set by setting one or more values in a second log in memory of the data storage device. The one or more host programmable tests on the data storage device are then executed. Results of the one or more host programmable tests are stored in a third log in memory of the data storage device.

Abstract: Data synchronization detection is provided between data identification and code demodulation in a data reproduction system, which performs data synchronization detection using code-modulated data. A specified bit pattern generated in a data codeword is calculated in each phase (bit), using a specified bit sequence pattern that is not generated in a specified phase of the data codeword. For example, a specified bit sequence pattern is generated only in a specified phase of the codeword. The positions of the data codeword partitions are thereby identified. Scrambling is then applied to the write data as required in order to ensure accurate synchronization detection.

Abstract: A system and method for accessing data stored on surfaces of discs in a disc drive utilizing more than one serpent per recording zone. The serpents are traversed using a defect descriptor table and one or more physical zone tables (PZTs). An Address Translation Logic Unit is configurable to use one or more PZTs to access multiple serpents per recording zone.

Abstract: A method and apparatus for detecting flaws requiring sparing of portions of storage media included as part of a hard disk drive are provided. A window of a selected portion of the storage medium is formed, and the density of defects detected within that window is calculated. If the density of defects exceeds a threshold amount, a signal is passed to the controller. The portion of the storage media containing the defects that caused the generation of the flag may then be spared. The present invention allows the potential for detected defects to significantly affect the ability of the storage medium to be assessed. Furthermore, the present invention does not require that the location of each defect be stored in memory. Accordingly, the present invention is economical to implement, and allows defects to be assessed in substantially real time and with improved accuracy.

Abstract: An apparatus for detecting an abnormality of a recorded signal of a recorder/player includes a plurality of recording/reproducing heads for recording/reproducing a signal onto/from a medium, and a determining portion for determining an abnormality of the recorded signal based on the signal reproduced by the recording/reproducing heads. While one recording/reproducing head records the signal of image and/or sound on the medium, the other recording/reproducing head reproduces the signal recorded by the recording/reproducing head. The determining portion determines the abnormality of the recorded signal by determining whether or not the signal reproduced from the medium is in a normal data format, or by determining whether or not an envelope of reproduced signals is greater than a predetermined level. Accordingly, when abnormality of recorded signal occurs due to a presence of foreign substances on the heads or from other problem sources, a user is immediately notified of such an abnormality.

Abstract: The present invention is a disc drive storage unit incorporating novel apparatus, data structure and method for uniquely identifying data written during each write command operation of the disc drive storage unit. The disc drive storage unit attaches unique write identification data (sequence data, time data, or both) to host computer data written during each sector write operation. The unique write identification data is attached through independent action of the disc drive storage unit. The unique write identification data is attached to the host computer data in such a way that the unique write identification data is transparent to the host computer. The data structure relates the host computer data to the unique write identification data. The method documents the manner in which unique identification data is attached to, and detached from, the host computer data.

Abstract: Object of this invention is to provide a servo writer capable of automatically controlling record current amount supplied to a writing head for every kind of magnetic tape when writing a servo signal on many kinds of magnetic tapes. The servo writer for writing a servo signal on magnetic tape MT which is fed out from a feeding reel and taken-up by a take-up reel includes writing head H1 that writes a servo signal on the magnetic tape MT, inspection head H2 for reading the servo signal formed on the downstream side and written on the magnetic tape MT, servo signal inspection part 16 that inspects the servo signal read by the inspection head H2, and current amount control part 17 that controls the amount of record current supplied to the writing head H1 based on the inspection result in the servo signal inspection part 16.

Abstract: A Gray code decoder for decoding input numbers includes a first select circuit that selects an M-bit Gray code number from a M-bit Gray code having a one-bit separation I and a two-bit separation J. A second select circuit selects an N-bit Gray code number from a N-bit Gray code, wherein K=M+N, M?N, and at least one of I and J is greater than, or equal to, 2N. A concatenate circuit concatenates the selected M-bit Gray code number and the selected N-bit Gray code number to produce a K-bit Gray code number.

Abstract: Methods of measuring position error due to pole tip protrusion are provided. In exemplary embodiments, a head having a write element is aligned to a track, and then pole tip protrusion is induced in the write element by writing to the track. The position error is measured after the pole tip protrusion has been induced. The position error can be measured just after the write element stops writing so that the position error is measured before the position error degrades or relaxes. Alignment of the head to the track, and measurement of the position error are accomplished while the head is over a servo segment of the track. The servo segment can be provided with separate alignment and evaluation portions for aligning the head and for measuring the position error, respectively. The alignment and evaluation portions can each encode two parallel sub-tracks, each with a different frequency.

Abstract: A new synchronous Partial Response Maximum Likelihood (PRML) servo is provided for a high track-per-inch disk-drive system. To increase the data capacity in hard disk drives (HDD), one can shorten the servo format and/or increase the track density. The new servo system has circuits that allow a high-performance and accurate system for positioning the read-write heads. The major circuits include burst demodulation, Viterbi detection, timing synchronization, and spin-up search. A highly linear discrete-fourier-transform (DFT) burst-demodulation circuit can demodulate high-density and low-signal-to-noise-ratio (SNR) position bursts. The Viterbi detection circuit includes a sync-mark detector and a Viterbi detector that are matched to at least two sets of Gray code ( e.g., ¼ rate and 4/12 rate) and pruned accordingly. The timing synchronization circuit includes phase restart and interpolating timing recovery (ITR) circuits to implement a fully digital timing recovery.

Abstract: A correction mechanism for use in a data storage system that allows data to be read even if the recorded data has been phase shifted.

Abstract: In order to increase the performance and reliability of devices including rotatable storage media, individual characteristics of device elements or heads can be determined and used to set performance criteria. The off-track capability and track mis-registration of an element or head can be determined and used to set individualized end-of-seek criteria for elements or heads of devices including rotatable storage media.

Abstract: Disclosed is a rotatable media storage device (RMSD) connectable to a host. The RMSD include a movable head to perform track following, a disk, and a synch mark detection circuit. The disk includes a circumferential track that has a plurality of embedded servo wedges utilized in track following. The synch mark detection circuit has a first detection mode and a second detection mode. In the first detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM of a servo header of an embedded servo wedge. In the second detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM and a wedge identifier of a servo header of an embedded servo wedge. The wedge ID is utilized in conjunction with the SSM to validate the servo synchronization signal.

Abstract: A method and apparatus is provided for maintaining data integrity. According to the method, a physical checksum calculation is performed on a block of data. After performing the physical checksum calculation, a logical check is performed on the data contained with the block of data. If the block of data passes the logical check, then the block of data may be written to nonvolatile memory. Thereafter, when the block of data is read from nonvolatile memory a physical checksum verification procedure is performed on the block of data to determine whether the block of data was corrupted after performing the logical check on the data contained with the block of data.

Abstract: A hard disk controller generates a read gate signal RG which has a predefined read start time and read end time set based on a sector pulse as a reference. A read data demodulation unit reproduces read data from a readout signal of medium by executing a read based on the read gate signal RG. A read gate optimization unit detects errors of read data demodulated by the data demodulation unit while varying the read start time and the read end time of the read gate signal RG, determines the read start time and the read end time at which the detected errors will be minimized and sets these in the read gate generation unit.

Abstract: A perpendicular magnetic recording type of disk drive having function of removing a component of a shift in a base line of a reproducing signal is to be disclosed. The disk drive has a read channel including an extracting unit which extracts the component of the shift in the base line of the reproducing signal. The extracting unit includes low-pass filters, and parameters of a lower cut-off frequency of the low-pass filter are adjusted in read operation.

Abstract: Systems are provided for improving servo-demodulation robustness. The SAM pattern is searched for in a servo wedge. If the SAM pattern is detected in the first servo wedge, a determination is made whether to characterize the detection of the SAM pattern as either a good SAM detection or a bad SAM detection. If the detection of the SAM pattern is characterized as a good SAM detection, one or more channel control values (e.g., servo AGC and/or PLL values) associated with the first servo wedge are used as (or to predict) starting values when beginning to read a next servo wedge. However, if the SAM pattern is not detected, or a detection is characterized as bad, one or more previously stored or predicted channel control values are used as (or to predict) starting values when beginning to read the next servo wedge.

Abstract: A smart retry operation, or set of retry procedures to be performed in sequence, that optimizes itself for a data storage device's individual characteristics, including variations across the data storage media and variations introduced as the device degrades over time, is disclosed. The data storage media (e.g. a disc in a disc drive) is divided into a number of zones and a separate smart retry operation is maintained for each zone. The data storage media is then tested to find errors correctable by the retry procedures. A statistical likelihood for each retry procedure is developed. The sequential order of the retry procedures in each zone's operation is then optimized based on the statistics. A single read/write retry sequences or separate read and write retry sequences may be maintained. The retry operations may be constantly re-optimized over the lifetime of the data storage device.