Abstract: A method for writing streaming audiovisual data to a disk drive is performed by organizing the data into clusters and commencing writing the clusters to the first physical sector encountered after the read/write head has settled to the desired track on the rotating disk. A cluster contains a number of data blocks corresponding to the number of physical sectors in an integer number of tracks on the disk, so that the writing of a single cluster is the writing to an integer number of full tracks on the disk. Even though the disk drive may have a physical index to identify the first physical sector in all the tracks, the writing of cluster data takes place-without regard to index position.

Abstract: Power control logic in a disk drive controls a mode of operation of operational logic of the disk drive for reduced power consumption. The operational logic includes a first and a second mode of operation, such that the second mode of operation consumes less power than the first mode of operation. The power control logic includes a memory, and is coupled to communication signals over an interface. In response to a predetermined communication signal, the power control logic configures the memory for storing data that is related to the predetermined communication signal.

Abstract: A system and method for interfacing a non-SCSI device to a computer network for communicating with a SCSI device attached to the computer network is disclosed. An interface receives a SCSI-based communication message from the network that is intended for the non-SCSI device. The SCSI-based communication can be formatted for transport over, for example, a TCP/IP transport stream and includes, for example, a command descriptor block and accompanying data. A translator device converts a first SCSI-based communication message to a corresponding first non-SCSI communication message that is recognizable by the non-SCSI device. A translator device also receives a second non-SCSI communication message from the non-SCSI device and converts the second non-SCSI communication message into a corresponding second SCSI-based communication message. The interface device, responsive to the second SCSI-based communication message, sends the second SCSI based communication message to the network.

Abstract: A data cache for an iSCSI network caches block-level data from WAN servers for use by clients (e.g., LANs). The cache authenticates itself to the WAN servers, and authenticates clients requesting cache access. Mechanisms are provided to prevent clients from accessing cached data intended for other clients.

Abstract: A read clock circuit for a disk drive includes a phase-locked loop/voltage controlled oscillator (VFO/PLL) and a frequency synthesizer. The VFO/PLL receives a servo sector transition signal that is related to detected transitions in a servo sector field of a magnetic recording disk, and outputs a servo frequency signal that is synchronous to the servo sector transition signal. The frequency synthesizer receives the servo frequency signal and generates the read clock signal that is synchronous with the servo frequency signal. In a banded recording disk drive the frequency synthesizer generates a unique read clock signal for each data band.

Abstract: A magnetic recording disk drive has head positioning servo sectors with servo sector numbers (SSNs) that are not recorded on the disk. The SSNs are encoded through the use of multiple servo sector types that are arranged in a specific sequence around the data tracks. The different servo sector types are identified by unique types of servo timing marks (STMs), which are used to locate the servo sectors. The SSNs that are used to identify the servo sectors on the track form a set or code of m fixed n-bit patterns. A SSN is determined when the STM types read from n sequential servo sectors match one of the fixed SSN pattems. A set or code of m servo sectors, where each servo sector is identified by a unique SSN pattern having length n, is denoted as an (m,n,d) code, where d is referred to as the minimum Hamming distance of the code. The Hamming distance between two patterns refers to the number of locations that are different between the two pattems.

Abstract: A method for adaptively formatting the multiple surfaces of data storage devices such as hard drives. The method ensures that all the drives have the same total data capacity and that the capacity in each data rate is the same from drive to drive. The method includes the step of dividing the data surfaces into warm and cold surfaces using a surface quality measurement. All cold surfaces are formatted with a predetermined cold format and all warm surfaces are formatted with a predetermined warm format. The cold and warm formats have different data capacities by means of different zone layouts, a different number of error correction code bytes per data block, or different track pitches. A second embodiment uses one of three different formats for each surface: cold, nominal, or hot. The cold and hot formats are designed to be mutually compensating in terms of data capacity and each drive has an equal number of cold and hot surfaces.

Abstract: A data recording disk drive is provided with a fixed block architecture sector format that eliminates the ID region. The servo region contains sector identification information in the form of a start-of-track indicating mark recorded in a selected sector of each track and a start-of sector indicating mark recorded in each sector. A full track number identifier is encoded in the position field within the servo region of each sector. A look-up table is built at format time to map bad sectors out of the disk drive. The table contains entries for each cluster of contiguous bad sectors, and is searched at runtime to provide conversion of logical sector location identifiers to physical sector location identifiers.

Abstract: A method and means is described wherein servo sectors written on a disk (or servo sections written on a tape) are equally spaced on a given track and read during seek, settle and track following operations. An algorithm is used to determine the allowable time separation between servo sectors (or sections) on a track and lengths of associated data sections, such as data sectors or variable length records, that may be accommodated on the disk or tape in such manner that each of the servo sectors (or sections) equally spaced on a given track is located within a data field of a data sector or within an identification region or immediately after an address indicating mark (such as address mark or index mark). The rate at which the servo sector (or section) is sampled is constant and independent of the number and lengths of the data sections.

Abstract: A sector servo, zone bit recording disk drive includes a sector architecture in which the recording head locates and identifies data sectors without using data ID fields, but instead using information obtained from electronic storage and from servo sectors which need not be adjacent to the data sectors. The tracks contain servo information and data, but not data sector ID information. The tracks in each zone are circumferentially divided into segments. Included in each segment is a number of data regions separated from one another by servo sectors. The data regions may contain partial data sectors and complete data sectors. The format information provided to identify and locate data sectors, including ones whose region locations are not adjacent to servo sectors, includes an entry for each region in the section.

Abstract: A data recording disk file with a fixed block architecture sector format that eliminates the ID region. The servo region contains sector identification information in the form of a start-of-track indicating mark recorded in a selected sector of each track and a start-of-sector indicating mark recorded in each sector. A full track number identifier is encoded in the position field within the servo region of each sector. A look-up table is built at format time to map bad sectors out of the disk file. The table contains entries for each cluster of contiguous bad sectors, and is searched at runtime to provide conversion of logical sector location identifiers to physical sector location identifiers.

Abstract: A method for operating a synchronized array of fixed block (FBA) formatted Direct Access Storage Devices (DASDs) to store and update variable-length (CKD) formatted records. This method is suitable for use with DASDs that obtain high recording density by using read and write head technology requiring "micro-jogging" to adjust for differing read and write head alignment or banded disk architecture having a higher block count in the outer tracks than in the inner tracks. Magneto-resistive heads may require micro-jogging to realign the write head for recording after reading the physical track location. The invention employs a DASD staggered array architecture having logical tracks consisting of diagonal-major sequences of consecutive blocks arranged in a predetermined wrap-around manner such as a topological cylinder or torus.

Abstract: A magnetic recording disk has servo sectors that are generally equally spaced on a given track and read during seek, settle, and track-following operations. An algorithm is used to determine the allowable time separation between servo sectors on a track and lengths of associated data sections that may be accommodated on the disk. In such a manner, the servo sectors are equally spaced on a given track and may be located within a data field of a data sector, within an identification region, or immediately after an address indicating mark (such as an address mark or an index mark). The rate at which the servo sectors are sampled is constant and independent of the number and lengths of the data sections. As a result of this independent relationship, this technique is suitable for a banded recording disk using sectored servo.

Abstract: A data recording disk file is provided with a fixed block architecture sector format that eliminates the ID region. The servo region contains sector identification information in the form of a start-of-track indicating mark recorded in a selected sector of each track and a start-of-sector indicating mark recorded in each sector. A full track number identifier is encoded in the position field within the servo region of each sector. A look-up table is built at format time to map bad sectors out of the disk file. The table contains entries for each cluster of contiguous bad sectors, and is searched at runtime to provide conversion of logical sector location identifiers to physical sector location identifiers.

Abstract: A data recording disk file is provided with fixed block address head positioning information that is readable off-track with no increase in error rate. The positioning information includes both identification information to provide radial and/or circumferential orientation for the recording head, and error handling information to ensure that the id information is properly read. Either or both of the id information and the error handling information for adjacent tracks are placed on the data storage disk at circumferentially offset positions to eliminate adjacent track interference, and at radially overlapped positions extending into the adjacent tracks to provide full readability when the head is off-track.

Abstract: A method and means is described wherein servo sectors written on a disk (or servo sections written on a tape) are equally spaced on a given track and read during seek, settle and track following operations. An algorithm is used to determine the allowable time separation between servo sectors (or sections) on a track and lengths of associated data sections, such as data sectors or variable length records, that may be accommodated on the disk or tape in such manner that each of the servo sectors (or sections) equally spaced on a given track is located within a data field of a data sector or within an identification region or immediately after an address indicating mark (such as address mark or index mark). The rate at which the servo sector (or section) is sampled is constant and independent of the number and lengths of the data sections.

Abstract: A rotary actuator data recording disk file is provided with a retro-reflective diffraction grating for use in measuring the angular position of the rotary actuator arm. The diffraction grating has a diffraction pattern whose pitch varies along the length of the diffraction grating. The variation in pitch is arranged such that, as the rotary actuator arm swings about its pivot axis and the diffraction grating moves across an incident light beam and simultaneously rotates with respect to it, the diffracted beam travels back along the incident path. Thus, the source and detector of a laser position measurement system can remain fixed while measuring the position of a rotary actuator arm to which the diffraction grating is affixed.

Abstract: A data recording apparatus, such as a disk drive or tape drive is described wherein servo sectors written on a disk (or servo sections written on a tape) are equally spaced on a given track and read during seek, settle and track following operations. An algorithm is used to determine the allowable time separation between servo sectors (or sections) on a track and lengths of associated data sections, such as data sectors or variable length records, that may be accommodated on the disk or tape in such manner that each of the servo sectors (or sections) equally spaced on a given track is located within a data field of a data sector or within an identification region or immediately after an address indicating mark (such as address mark or index mark). The rate at which the servo sector (or section) is sampled is constant and independent of the number and lengths of the data sections.

Abstract: One or more data-storing disk devices support logical tracks extending between radial recording zones of tracks in the device(s). Each data-storing disk in the device(s) is formatted into a plurality of radial recording zones of physical tracks, each radial recording zone having a like number of physical tracks, each physical track may be one circumvolution of a single spiral track. The physical tracks in the respective recording zones store a different number of data bytes. Each logical track including a plurality of said physical tracks; at least one of the physical tracks in each of the logical tracks is in a different one of the radial recording zones in different ones of the devices or in a single device. Described are an extended logical track and extended logical cylinder accessing methods and apparatus. Not all of the physical tracks of any of the devices or recording zones need be a member of any logical track.

Abstract: A method and means is described for writing data on a recording medium, such as a disk or tape, containing servo samples in such manner that the number of servo samples is increased with a minimal increase in overhead (non-data) regions. The tracks on the medium are divided into a plurality of maxi sections, each of which contains all fields with servo and associated overhead information and also a data field. At least one micro servo section containing only a portion of said information is located within each data field.As each micro servo section passes by an associated recording head, writing and reading of data is temporarily interrupted, but resumed when the micro servo section moves beyond the head, in such manner as to require minimal resynchronization of said data during reading.Using a phase continuous clock, data is written in both portions of a data field to either side of each micro servo section in one pass of the disk or tape relative to the head.