Abstract: An apparatus and method for correcting for track misregistration when a slider or head assembly contains a separate read element and write element. The offset is determined at a first position and at a second position of the actuator arm assembly. From these offsets a constant and a multiplier are determined for determining an offset as a function of the cylinder location. Also disclosed is a method and apparatus for minimizing distance traveled to prevent misregistration when repositioning between the read element and a write element. The read element is intentionally offset from the write element at an angle so as to minimize the distance traveled across the disk.

Abstract: A cooling system provides redundant fault-tolerant cooling to electrical devices in an electrical apparatus and comprises a plurality N+1 individual cooling fans, N cooling fans being required to provide cooling of the devices and further comprises monitor logic for monitoring the status of the plurality of cooling fans and for issuing a non-critical warning to the apparatus in the event of failure of one of the cooling fans, the logic being further operable, in the event of a failure in the logic, to issue a non-critical warning to the apparatus.

Abstract: Described is a technique for transferring data between a device controller and a device in a data storage subsystem. The controller has a data buffer through which passes data being transferred to and from the device. The controller communicates with the device by means of low level multi sector Read/Write orders and the data requested by the controller is transferred between device and controller in the form of 32, 64 or 128 byte packets. The device has a relatively small data buffer which can store one packet of data at a time. While one order is executing on the device, the controller is able to issue subsequent orders. One of these orders is an EXTEND order which orders the device to continue reading beyond the data specified in the read order currently executing on the device. The EXTEND order also allows implementation of `back to back` writes.

Abstract: Method, with structure, of production of precision head/disk interfaces for near contact recording in a low viscosity liquid lubricant film. Triangular shaped bearing pads in an assembled hard drive are brought to bear upon a rotating lubricated disk to dislodge, smooth and polish any residing asperity. The triangular shape of the bearing pads sweeps away and directs to the outer edge of the disk any of the remaining fine carbon sputtering debris which is loosened as the bearing pads are drawn from the inner dimension to the outer dimension of the disk.

Abstract: The invention is intended to provide a magnetic recording medium suitable for longitudinal recording, which has low medium noise and high coercivity. A magnetic recording medium includes a substrate 1 and a magnetic layer 2 formed on the substrate 1. The magnetic layer 2 consists of a mixture of a magnetic alloy and a non-magnetic compound. The magnetic alloy is Co-based, Fe-based, or CoFe-based, and the non-magnetic compound is selected from a group consisting of oxides and nitrides. The volume percentage of the non-magnetic compound in the entire volume of the mixed magnetic alloy and non-magnetic compound is preferably not less than about 2% and not more than about 30%.

Abstract: A vacuum deposition system is shown in the form of a sputtering system for rigid disk substrates which uses a single vacuum envelope and a single transport to avoid multiple pump downs or valved isolation structures during the multiple coating processes or the transfer of workpieces between conveyer devices. Work stations carried by a modular processing unit provide a slotted opening through which work pieces supported on the transport enter and leave the work station and which affords sufficient restriction to enable a processing gas atmosphere to be maintained within the work station that is above the pressure of the vacuum envelope while being isolated from the adjoining work stations. The work stations are supported on and readily releasable from the modular processing units to allow service and target replacement to occur offline.

Abstract: The inside wall of a head/disk enclosure is given a surface broad enough to adsorb and release easily a large amount of water vapor. In a first embodiment, the inside surface is treated by anodic oxidation using oxalic acid. In a second embodiment, the inside surface is treated with sodium carbonate and sodium chromate. In a third embodiment, the surface was etched with acid. The water adsorption capability acts as a buffer to prevent extremes of relative humidity within the enclosure.

Abstract: The present invention overcomes the problems that accompany the use of ramps to load and unload transducer carrying sliders in rigid magnetic disk data storage devices. The tracks in the region where the slider loads and unloads are read and the errors recorded following each slider loading operation. One technique is to track the error increase and identify imminent device failure when the rate of error increase during a given number of the most recent slider load cycles exceeds a threshold value. In another mode, a dedicated sequence of tracks is recorded at an increased linear density to assure that read errors occur to enable a more effective comparative evaluation. This makes possible a two stage evaluation, a first threshold number of errors indicative of degrading performance which initiates lower actuator velocity to inhibit further degradation and a second threshold error quantity that indicates imminent catastrophic failure and triggers a warning to the system user.

Abstract: A controller 40 of an HDC 30 is connected to a drive 28, and an arm is rotated through a predetermined angle. A magnetic head 20 on the arm comprises a recording element and a reproduction element. A bias current is supplied to the magnetic head 20 from the controller 40 through a driver 36A and a switching circuit 32A, and the magnetic field of the disk 18A is detected in a detector 38A through a switching circuit 32A. The switching circuit 32A inverts the polarity of a current applied to the magnetic head 20A, by a signal from the controller 40 corresponding to a skew angle. Accordingly, the direction of the bias magnetic field is changed, the effective sensitivity position of the reproduction element approaches the recording element, and off-track can be reduced.

Abstract: The back edge of a disk drive slider is used to remove debris from disk media by slowly sweeping it from the inner diameter of the disk to the outer diameter of the disk while the disk is rotating backwards from normal. The sweeping operation is completed while the disks are still gaining rotational speed so that liftoff velocity is not achieved. Material accumulated on the back edge of the slider is either dumped at the outer diameter of the disk, or remains on the back edge of the slider as normal operation is commenced.

Abstract: The present invention relates to a method and apparatus for writing servo tracks of a magnetic disk unit, and has an object of providing a servo track writing method and apparatus which can reduce a mechanical vibration of a head in the steady state and can shorten a settling time of the system. A detecting face is set in the vicinity of a head arm end portion 22 of a magnetic disk unit 2, and a capacitance probe 28 is provided as a gap detecting means for detecting a gap in a head moving direction between the detecting face and the head arm end portion 22. Further provided are a rotary positioner 26 as a positioning means for moving the capacitance probe 28 in the head moving direction to position it at a target position, and a head drive system control means for moving a head 14 of the magnetic disk unit 2 so that the gap is kept constant, to position the head 14 at a predetermined servo track writing position.

Abstract: An adapter connected between a host computer and disk storage devices provides interfaces for connecting to the host computer and the disk storage devices having the same interface design. The adapter itself includes control means for building a redundant disk storage system. Moreover, the adapter itself includes means for detecting and indicating a failed disk storage device, means for replacing the failed disk storage device, and means for rebuilding a redundant disk storage system after the replacement of disk storage devices. A command is configured so that the host computer can have access to each of disk storage devices for maintenance purposes. The adapter makes it easy to configure a highly reliable redundant disk storage system for a small computer system without any change to existing hardware or software.

Abstract: A disk file has a frame with a non-rotatable shaft (2) extending in an axial direction between opposed wall portions of the frame. The shaft is clamped at one end to the frame by a screw (8) passing through an opening in the wall and axially into the shaft. This arrangement is susceptible to tilting of the shaft due to differential thermal expansion if the frame wall (1) and the shaft have dissimilar coefficients of thermal expansion. A bush (9) is located between the screw and the shaft. The bush is held in the wall by an interference fit, and has a coefficient of thermal expansion similar to that of the shaft. The inclusion of the bush greatly reduces problems due to differential thermal expansion.

Abstract: A multipath channel apparatus for a data storage device wherein data is stored on a storage medium and is read from the storage medium by a transducer or for a data communications system wherein data is transmitted to a receiver. A data channel having a plurality of data paths is operatively connected to the transducer to receive data read from the storage medium by the transducer, or operatively connected to receive data demodulated by the receiver or base band data received by the receiver. Preferably, each of the data paths has a differing parameter value. An error checking unit checks customer and redundancy data from each of the data paths. A selecting unit, which is responsive to the error checking unit, selects data from one of the data paths. In a preferred embodiment, the data stored on a storage medium includes a data field and an error correcting code field, and the customer and redundancy data from each of the data paths is checked using a calculated error correcting code sydrome.

Abstract: A data storage subsystem and method for transferring data from a storage subsystem to a connected host data processing system are described. The subsystem comprises a device controller connected to one or more direct access storage devices e.g. disk drives. The host data processing system issues data transfer commands to the subsystem to initiate transfer of data between the host processing system and the device(s) associated with the data storage subsystem. Read/write data is transferred directly from device to host via a buffer controller. For a read operation, the read command from the host data processing system specifies the data to be transferred and the start address in host memory to which the data should be sent. The device controller of the data storage subsystem is capable of respecifying or amending the start address specified by the host in the rad command. This provides a performance bonefit for split data transfers.

Abstract: A clamp ring for clamping disks to a rotating hub includes a inner diameter leg portion, a cross member portion and a disk contacting portion. A cross sectional view of the clamp ring is N-shaped. The clamp ring is heated so that it thermally expands to a diameter that is larger than the outer diameter of the hub. A thermally expanded clamp ring is placed on the top of the disk stack which has at least one disk. An axial load is placed on the inner diameter leg portion as the clamp ring cools. The inner diameter grips the hub as it cools. The cross member is compressed as the clamp ring cools. The disk contacting portion moves slightly as the clamp ring cools. This movement counteracts the outward movement of the disk contacting portion of the clamp during loading resulting in little tendency to cone the disk. The result is a disk stack clamped without a resulting radial load on the disks.

Abstract: The lubricant film for a near contact magnetic recording device is maintained by a closed loop servo control for a recirculating lubricant supply system. A reservoir closely overlies the disk data surface and includes a heater for controlling the temperature difference between the reservoir and the disk surface. Decreasing the heater current reduces the film thickness and increasing the heater current increases the film thickness. A wick system gathers lubricant from within the disk enclosure, which may have been spun off the disk or condensed from the lubricant laden atmosphere and returns the lubricant by capillary action to the reservoir. Further, the reservoir includes two portions which are independently controllable. The first overlies the data band of the disk and the second overlies the start/stop zone and the head when the latter is not operational and parked at the nonoperating location.

Abstract: In a redundant array of disk storage units which independently accesses data blocks on different units and which uses parity blocks for data protection, parity blocks are confined to specific address ranges of each respective disk unit (rows of the array), each row containing multiple parity blocks. Each parity block represents the exclusive-OR of a stripe of data blocks located on a diagonal of the array. Where data accesses exhibit locality of reference in certain rows, this arrangement distributes the burden of updating parity more equally than a conventional RAID level 5. Additionally, because a "row" corresponds to a particular annular region of a disk surface on each respective disk unit, parity blocks can be located at optimal logical addresses or physical regions of the disk surface to simplify address translation and/or further improve performance.

Abstract: Disclosed is a disk drive for storing representations of data. The disk drive includes a housing or enclosure. At least one disk is rotatably attached to the housing. Also attached to the housing is an actuator. A transducing head is attached to one end of the actuator and is positioned to pass near the disk. Attached on the other end of the actuator is a coil which makes up a portion of a voice coil motor. Another portion of the voice coil motor is a magnet positioned near the coil. The housing includes at least one recess or opening which holds the magnet on the outside of the housing yet near the coil.

Abstract: An object of the present invention is to specify two disk drive apparatuses which are connected to an AT interface as a master or slave HDD for local or cable selection by only one jumper block. A disk drive apparatus connected to data processing means through a plurality of interface lines including one interface line connected to a first voltage level of said data processing means, including:a plurality of connection points connected respectively to said plurality of interface lines,a first connection point capable of being selectively connected to said one interface line,a second connection point kept at a floating voltage,a third connection point tied to the first voltage level,a fourth connection point tied to a second voltage level and selectively connected to one of said first, second, and third connection points, andcontrol means connected to said fourth connection point and recognizes itself as a first or second disk drive apparatus by detecting a voltage level of the fourth connection point.