Abstract: A multi-state preamplifier having a first detector and a second detector provides voltage-sensing and current-sensing signal amplification, respectively. Either the first detector or the second detector is selected and switched active at any given time, producing an amplified signal representing either the signal voltage developed across the MR element or the signal current flowing through the MR element, respectively. The switching process to activate either the first detector or the second detector is carried out by a detector determining circuit connected to a disk drive control unit. The detector giving the optimum high frequency bandwidth for the preamplifier is chosen based on the resistance of the MR element coupled with the input interconnect network characteristic and parasitic impedances.

Abstract: Aspects for automatic code version update detection and distribution for an application program running on a computer system in a computer network are described. In a method aspect, the method includes providing two agent processes, a slave agent and a master agent, on an agent system in the computer network. A request is received in the slave agent from a manager system in the computer network, the request including an appropriate code version of the running application for response. A determination of whether the slave agent can fulfill the request at the appropriate code version is made, and an automatic updating of the agent system occurs when the request cannot be fulfilled at the appropriate code version.

Abstract: A method and apparatus for monitoring the quality of the readback signal of data written on a magnetic recording disk in a disk drive and for limiting data loss due to physical damage at a slider/disk interface. The amplitude of a read signal is continuously monitored in the read channel, either by directly measuring the read signal amplitude or by monitoring the amplification level of the automatic gain control (AGC) circuit in the read channel which is inversely proportional to the read signal amplitude. If the amplitude of the monitored read signal decreases below a chosen level, the location of the data on the disk track is flagged as possibly damaged. The data is rewritten at the same location and then reread to see if full recovery of the degraded data is possible. If the amplitude read signal of the rewritten data is greater than a chosen level, the disk track is judged to be usable and normal operation continues.

Abstract: Method and system aspects for more intuitively presenting a relationship for static chart data from at least two static charts are described. In a method aspect and system for providing same, the method includes obtaining data from first and second static charts. The data from the first static chart is displayed as a beginning chart. The displayed data from the first static chart is adjusted to visually indicate a change in the data required by the data from the second static chart as an ending chart.

Abstract: A method for deriving format data for a functional disk drive volume includes the following steps. Initially format data is written onto a reference functional disk drive volume. A reference functional volume format data structure is then established which associates reference functional volume functional track values with physical track addresses for each track of the functional volume for which the format data was written. Thereafter, when a command is received to format a new functional volume, a copy of the reference functional volume format data structure is derived. Then, when a write command, for example, directed to a track of the new functional volume is received, the copy of the reference functional volume format data structure is used to access a corresponding formatted track from the reference physical disk drive volume. If a write action is then performed on the corresponding formatted track, the updated track is then written back to a physical disk drive at a new location.

Abstract: The invention implements a method for enabling overlapped performance of data processing actions during data transfers between a DSS and a host processor. The DSS includes a state queue which holds a plurality of states, each state comprising a self-contained procedure which, upon execution, determines a readiness to execute of an associated task. The method initially determines an amount of available time during a data transfer wherein a front-end processor of the DSS would otherwise be idle. The method then causes the front-end processor to extract and execute a first state from the state queue during the data transfer, if available time during the data transfer exceeds or is equal to an estimated execution time of the first state. Then, if a task associated with the first state is found to be ready to execute, that task is listed on a task work queue for execution subsequent to the data transfer.

Abstract: A voltage-biasing, voltage-sensing differential preamplifier having a high input impedance preamplifier circuit to amplify magnetic data readback signals from a magnetoresistive (MR) sensor and feedback circuits to simultaneously hold the electrical center of the MR sensor at a prescribed potential (usually ground) while applying a predetermined constant differential voltage-bias across the MR element. The feedback circuits provide a stable operating point for the MR sensor at the desired bias-voltage, and maintain the average potential on the MR sensor at or near the disk substrate potential to limit the destructive effects of MR sensor contact with conducting asperities.

Abstract: A system and method for removing a file from a system is disclosed. The system includes a storage device and a virtual storage. The file has associated metadata that indicates a location of the file on the storage device. A first copy of the associated metadata resides on the virtual storage. A second copy of the associated metadata resides on the storage device. The system and method include marking the file as removed and updating the second copy of the associated metadata substantially immediately if the system is to run out of space on the storage device and a next scheduled update of the second copy of the associated metadata has not occurred. The system and method further include indicating that the location is available for storing data substantially immediately if the system is to run out of space on the storage device and the next scheduled update has not occurred.

Abstract: A method and apparatus for identifying a least recently used item of a set or group of items is disclosed. In accordance the method, a count value is associated with each item. A first count value is assigned to an oldest item, a second count value is assigned to a newest item, and items having an age between the oldest and newest are assigned successive count values between the first and second count values in accordance with the age of the item. When an item is accessed, a pivot count value associated with the accessed item is determined. Each count value between the pivot count value and second count value is incremented in the direction of the first count value. The count value associated with the accessed item is then reset to the second count value. The least recently used item is identified as that item associated the first count value. One or more embodiments of the invention comprise apparatus for performing the method of the invention.

Abstract: A milliactuator integrated with driver and relative position error sensor circuits formed on a single silicon substrate. The integrated milliactuator/electronics module is positioned between the suspension and the slider/transducer assembly to provide rapid, small motion position control of the slider/transducer over data tracks on the disk of a magnetic disk drive. Integration of the milliactuator electronics with the milliactuator reduces parasitic loading and interference problems with the magnetic transducer signals. Electronic circuits are built on a silicon wafer followed by deposition of a planarization layer and a ground plane layer for isolation from the milliactuator which is then built on top of the circuits.

Abstract: A data storage system includes at least first, second and third virtual storage volumes, the second and third virtual storage volumes being remotely coupled as a PPRC pair to enable a mirroring of data therebetween. The storage system is responsive to a snapshot command from a host processor, to cause transfer of the directory of the first virtual storage volume to the second virtual storage volume. The storage system then invokes a PPRC mirroring procedure which (i) detects an unsynchronized condition between the second and third virtual storage volumes (upon transfer of the directory from the first virtual storage volume to the second virtual storage volume), and (ii) causes a transfer of data, pointed to by the transferred directory, to the third virtual storage volume, until the second and third virtual storage volumes are again in synchronism.

Abstract: The present invention provides a disk drive, a loading/unloading apparatus, and a method for controlling the apparatus, capable of improving the reliability of data by performing stable speed control.

Abstract: A ferrofluid seal for a hard disk drive actuator bearing has two circular plates which are axially spaced apart about a nonmagnetic pivot shaft of the actuator. The plates are parallel and in close proximity to one another. The upper plate is made of magnetically-conductive steel and is mounted to a stationary sleeve which surrounds the shaft. The lower plate is mounted to the shaft and has an annular magnet with pole pieces on an upper surface. A magnetic ferrofluid is located between the magnet and the upper plate to complete the magnetic circuit and form a seal. The ferrofluid seal prevents bearing emissions such as grease oil vapor and aerosol droplets from contaminating the disk drive.

Abstract: The present invention teaches the realization of a stable feedback control by selecting an optimal notch filter in an apparatus, such as a hard disk drive, that employs a positioning apparatus, such as an actuator, for positioning an object. The present invention further teaches the derivation of a frequency characteristic of a control loop excluding a notch filter by employing a method that does not damage a positioning apparatus. The present invention further teaches the method of adjusting a notch filter in accordance with a change of the resonant frequency of an actuator caused by the temperature fluctuations to prevent any deterioration of a feedback control performance.

Abstract: A cleaning apparatus for cleaning sensitive components such as those used in the disk drive and semi-conductor industries. The cleaning apparatus of the present invention includes of an adhesive tip mounted on a handle. The adhesive tip may be fixedly or rotatably mounted on the handle, and is further comprised of an adhesive film which may be wrapped about the handle or formed over a more compliant or more resilient surface. The adhesive film is preferably a low residue, low out gassing material which may easily remove particles from the surface of precision components without further contaminating the component.

Abstract: A test connector for making electrical tests on a disk drive on a high volume manufacturing line. The test connector comprises a high density connector header for electrical connection to a disk drive electrical connector fixed to a printed circuit board (PCB) card having well-separated, large area contact pads electrically connected to the contacts on the connector header. The well-separated, large area contact pads on the test connector provide contact points for test probes from automated testers on the manufacturing line. Use of the test connector with its well-separated, large area contacts increases the reliability of electrical testing procedures with automated testers by reducing accidental shorting between test probes and by increasing contact alignment tolerances.

Abstract: The present invention is a preampifier circuit for magnetoresistive (MR) elements which has a high imput impedance with respect to the MR resistance so that the resultant system would not be sensitive to the series input inductance of the leads necessary to connect the MR element with the preamplifier. With former preamplifiers, nearly all are low impedance types, (using either BiCMOS or BiPolar technology), or differential (using BiPolar technology). The present invention fills a need in the prior art by providing a preamplifier curcuit using BiCMOS technology with a high input impedance, and single ended (SE) topology for minimum power dissipation.

Abstract: An FPC cable which is excellent in noise resisting property, manufacturing cost, mounting operability to a carriage, and maintenance. The FPC cable includes a spacer and a reinforcing plate. In the patterned surface of the FPC, a head pad to which a head wire is bonded is formed on a pad forming portion and a preamplifier chip is mounted on a device mounting portion. Wiring patterns are linearly connected between the head pad and the preamplifier chip and between the preamplifier chip and an I/O-side end portion, respectively. In the spacer, a cavity is formed for storing the preamplifier chip. The reinforcing plate is inserted into the space formed by folding back the pad forming portion, and the spacer is engaged with the device mounting device, thereby constituting a magnetic-head-side end portion.

Abstract: A storage system is provided for storing data for a computer system where the storage capacity can be incrementally increased without disrupting the operations of the storage system. The storage system comprises a base unit, and a plurality of modular units. The modular units are inserted into the system as increased storage capacity is required. Each modular unit has an enclosure comprising top, bottom, and side walls. The bottom and top walls each have at least one power connector and data transmission connector. The bottom wall of a first modular unit enclosure attaches to the base unit enclosure and the top wall of the first modular unit enclosure can attach to the bottom wall of a second modular unit enclosure. At least one back plane is provided in each modular unit for providing attachment for a set of storage devices.

Abstract: A method and apparatus for adjusting the height of a set of load/unload lift cams with respect to the axial height of an associated stack of disks. The method steps comprise supporting load/unload lift cams with an adjustment tool, measuring the relative height of the load/unload lift cams with respect to the stack of disks in the axial direction with a non-contact transducer, and fixing the load/unload lift cams at a registered height with respect to the stack of disks.