Abstract: A first string, having a first string value, that is associated with a sample set of material is received, wherein a second string, having a complementary value relative to the first string value, is also associated with the sample set of material. A determinative hash is generated using the first string value and a symmetric generator polynomial. A second hash, corresponding to the second string, is generated directly from the determinative hash. A canonized hash is generated using the determinative hash and the second hash. It is determined whether at least one of the first string or the second string is stored in string storage that is configured to store a plurality of strings, including by searching a hash table for the canonized hash; in the event it is determined that at least one of the first string or the second string is not stored in the string storage, at least one of the first string or the second string is stored in the string storage.

Abstract: A first string, having a first string value, that is associated with a sample set of material is received, wherein a second string, having a complementary value relative to the first string value, is also associated with the sample set of material. A determinative hash is generated using the first string value and a symmetric generator polynomial. A second hash, corresponding to the second string, is generated directly from the determinative hash. A canonized hash is generated using the determinative hash and the second hash. It is determined whether at least one of the first string or the second string is stored in string storage that is configured to store a plurality of strings, including by searching a hash table for the canonized hash; in the event it is determined that at least one of the first string or the second string is not stored in the string storage, at least one of the first string or the second string is stored in the string storage.

Abstract: A first string, having a first string value, that is associated with a sample set of material is received where a second string, having a complementary value relative to the first string value, is also associated with the sample set of material. A reversible hash generator is used to generate a determinative hash using the first string value, where a second hash, corresponding to the second string, is able to be determined directly from the determinative hash and without the reversible hash generator processing the complementary value of the second string. It is determined whether at least one of the first string or the second string is stored in a memory using the determinative hash.

Abstract: A disk drive includes a controller and at least one disk, which may include a first I-region, a second I-region, and an E-region. The first and second I-region may have a first final logical block address (LBA) and a second final LBA, respectively. The controller may be configured to cause information to be written to the first I-region and the second I-region using a first type and a second type of magnetic recording, respectively. The controller also may be configured to set at least one of the first final LBA or the second final LBA to a final LBA value higher than the at least one of the first final LBA or the second final LBA, respectively, after writing user data to at least a portion of the first I-region or the second I-region and without removing the user data.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and location information such as the track-ID. The juxtaposition of sequences in the servo wedges is additionally constrained to increase the detectability of the contribution of adjacent sequences in the read signal. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and positional information such as the track-ID. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences. The servo system detects the sequences in the signal from the read head using a set of digital filters for the set of encoded sequences.

Abstract: Disk drives are described in which blocks of data spanning multiple sectors are encoded into a plurality of codewords which are then divided into segments that are physically separated (distributed) on the disk surface over multiple sectors in a distributed codeword block so that the codewords have an improved worst case SNR in comparison to individual sectors. This results in more even SNR performance for each codeword, which improves the performance for portions of a track which have lower than the average SNR. Embodiments are described in which the distributed codeword blocks span across tracks.

Abstract: A computer system includes a host and a disk drive apparatus communicatively coupled to the host. The disk drive includes at least one disk having two major surfaces divided into a plurality of regions. A region includes a start logical block address and a maximum logical block address and an end/final logical block address. After the host writes to the end/final logical block address, it queries the disk drive to see if a region has more capacity. If the disk drive returns a new end/final logical block address, the host frees the allocation up to the new final/end logical block address.

Abstract: Techniques for processing signals read-back from a disk of a hard disk drive are described. In one example, a hard disk drive device generates a signal associated with a first position within a width of the data track. The first position may correspond to the center of a data track. The hard disk drive device generates a signal associated with a second position within a width of the data track. The second position may be located at a distance of approximately 10% of the track width from the track center. The hard disk drive device combines the signals and applies as signal conditioning technique to the combined signal.

Abstract: A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Abstract: A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Abstract: A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Abstract: A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Abstract: A receiver utilizes a plurality of read elements, each generating a read-back signal in response to a data track positioned beneath the read element. The plurality of read-back signals are each provided to at least one space-time interference cancellation filter, which generates a filtered output that maximizes a signal associated with one of the plurality of data tracks. The filtered output is provided to a one-dimensional Viterbi detector, which is configured to generate in response an output representative of a data sequence written to one of the plurality of data tracks.

Abstract: A magnetic storage system includes a magnetic storage medium, a random-access memory (RAM), and a controller. The controller interfaces with both the magnetic storage medium and the RAM, and implements a refresh algorithm that determines when a data track on the magnetic storage medium should be refreshed. The controller maintains in the magnetic storage medium a plurality of finer-granularity damage count tables, each table having finer-granularity damage counts each representing damage to one or more sectors within each of the plurality of tracks associated with the table. The controller maintains in RAM a plurality of track-level damage count values, each associated with one of the plurality of data tracks and representing estimated damage to one of the plurality of data tracks. Based on data written to the plurality of data tracks, the controller utilizes finer-granularity damage count tables stored in the magnetic media to update the track-level damage.

Abstract: A disk drive includes an environmental monitor, a controller and a writing mechanism. The controller acts in response to an output from the environmental monitor to determine if the data capacity of a disk drive could be increased from a first value to a second value. The controller determines the second increased value. The writing mechanism, controlled by the controller, writes data to the disk to realize the increased data capacity of the disk drive. A method for increasing the data capacity of a disk drive from the factory settings for data capacity includes determining if the disk drive is in a favorable or stable environment, writing data to at least one portion of the disk drive at a higher capacity than the factory setting for the at least one portion of the disk drive, and resetting the capacity for at least one portion of the disk drive.

Abstract: A disk drive having at least one disk with a major disk surface that includes a first region including a plurality of tracks and a second region including a plurality of tracks. The first and second region are separated by a guard band. The track or tracks near the guard band have a track width that is greater than the track widths of the tracks more distant from the guard band, such as those in the middle of the first and second regions as this reduces the occurrence of far track interference.

Abstract: Shingled magnetic recording (SMR) devices according to embodiments of the invention include unshingled cache regions that can be used for storage of data. The unshingled cache regions can be used in a variety of flexible ways including in an implementation of write-twice caching or for opportunistic temporary storage to improve performance. The cache regions can be offset between top and bottom surfaces of the disk and staggered between disks to provide shorter seek times to the nearest cache region. Embodiments of the invention are adapted for use with symmetric or asymmetric heads.

Abstract: Methods are described that allow disk drives, such as shingle-written magnetic recording (SMR) drives, to recover an Indirection Address Table mapping of LBAs to PBAs after an emergency power off (EPO). Indirection Address Table (IAT) snapshots are periodically written inline with user data stores, and in one embodiment Cumulative Delta Lists (CDLs) with incremental address update information are stored between snapshots. In an embodiment of the invention, when an imminent loss of power is detected, the current CDL, covering IAT updates not yet written to disk, is saved to a nonvolatile memory. The IAT snapshots combined with the set of CDLs provide the information needed to recreate the current Indirection Address Table when power is restored after an emergency power loss. In an alternative embodiment the CDL is obviated by including metadata in the sector that encodes the address indirection mapping and the last snapshot ID.

Abstract: A method for writing information to a magnetizable disk surface on a disk drive includes designating a plurality of regions on a disk where information is to be stored, writing information representing data to a first track in at least one of the plurality of regions, writing information representing data to a second track in the at least one of the plurality of regions, the information written to the second track overwriting a portion of the first track, and determining an amount of the first track that is overwritten based on a performance factor. Determining an amount of the first track that is overwritten is done or accomplished on the fly. The amount to overwrite the track is done in the field rather than in a factory or manufacturing facility.