Abstract:
A network management system includes a domain administrating server (DAS) that stores a virtual catalog representing an overview of all files distributively stored across a network domain currently or in the past. The current and historical file information is used for assisting in auditing or locating files located anywhere in the domain. The current file information is used for assisting in transferring files across the domain. The domain administrating server (DAS) also includes a rule-base driven artificial administrator for monitoring and reacting to domain-wide alert reports and for detecting problematic trends in domain-wide performance based on information collected from the network domain.
Abstract:
A magnetic parking device for locking an actuator in a disk drive (30) over a transducer landing zone (61). A magnetically permeable capture member (100) provided on an actuator arm (50) magnetically interacts with a permanent locking magnet (90) thereby locking a transducer (38) in the landing zone (61). A bucking coil (85) is provided arranged about the permanent locking magnet (90) for passing a current to generate a magnetic field with polarity opposite that provided by the permanent locking magnet (90) to neutralize the magnetic field to release the actuator from the parked state.
Abstract:
A device for measuring flying heights of a read/write head (30) in a disk drive down to zero microinches using interferometry, wherein the flying height of the head above the disk surface is calculated by directing white light to the under side of a rotating disk (20). A thin metallic layer (22) on the disk acts as a beam splitter, reflecting a first portion of the beam back downward, and allowing a second portion of the beam to pass therethrough to be reflected back downward off of the bottom surface of the read/write head. Once reflected, the two portions will combine to form an interference pattern. This pattern is then input to a spectrometer, which creates an intensity profile to represent the unique height of the air-bearing slider (36) above the beamsplitter layer. The flying height is finally determined by subtracting from this height the thickness of the spacer layer (24).
Abstract:
A method and apparatus for performing error detection on data transfer through a parallel interface port (18) at a substantially increased data transfer rate with a minimum of handshaking. Blocks of data are transferred between a sending device (12) and a receiving device (14 and/or 16), and each of the respective devices maintain a checksum (50, 52a, 52b). Each checksum comprises an initial value, and added to that value is the value of each data byte transferred through the parallel port interface. After a block of data bytes has been transferred, the checksum maintained by the sending device and the receiving device are compared. If the checksums are equal, no error is assumed to have occurred during the data transfer. If the checksums are not equal, an error is assumed to have occurred during the data transfer, and the data is retransferred with the previously transferred block discarded.
Abstract:
A task assigning system within a dual actuator disk drive system wherein each task has a cylinder address comprising a plurality of registers, each register having a unique address and a plurality of fields for storing a task including the cylinder address associated with the tasks, a queue RAM (14) comprising a header register, the header register having a plurality of fields, an insertion means for inserting and ordering the registers into the queue RAM (14) when a task is first stored into the register, a first means (28) for assigning tasks stored in the queue RAM (14) to a first actuator (63) of the dual actuators in the sequence of increasing value of the cylinder addresses of tasks stored in the registers in the queue RAM (14) and a second means (30) for assigning tasks stored in the queue RAM (14) to a second actuator (61) of the dual actuators (63, 61) in the sequence of decreasing values of the cylinder addresses of the tasks stored in the registers in the queue RAM (14).
Abstract:
A queue system comprising a plurality of queues (20-23) where each is defined by a set of criteria, the queue system comprises a plurality of header registers (1-3) where each header register defines a queue in the queue system and a plurality of task registers where each task register can be associated with each queue (20-23) in the queue system. Each header register has a unique address and contains a previous field and a next field. Each previous field and said next field store the address of another register in a given queue such that each queue is formed in a double link structure. Control means is provided for dynamically assigning task registers to queues (20-23) by controlling the addresses in the previous and next fields in each header and task registers such that each of said task registers is always assigned to a queue in the queue system.
Abstract:
A magnetic recording medium employing a thin layer of nonmagnetic material (22) separating a soft magnetic layer (18) and a relatively thicker magnetic recording layer (16) is disclosed. The magnetic recording medium may incorporate conventional magnetic recording materials with the thin nonmagnetic layer (22) being silicon, chromium or carbon. The magnetic recording medium may be prepared by sputtering or other vapor deposition methods. A method for preparing a magnetic recording medium according to the present invention deposits the magnetic recording layer (16) either directly on a substrate (12), or, optionally, on a nucleating layer (14). The thin nonmagnetic layer (22) separates the magnetic recording layer (16) from the soft magnetic layer (18). A protective layer (20) overlies the soft magnetic layer (18). The deposition is achieved under conditions that maintain integrity of the magnetic recording layer.
Abstract:
A two and one half inch form factor disk drive has a plurality of disks (24) for increased data storage capacitor (at least 40 Mb). A spin motor (Figs. 4, 5) has reduced vibration by employing two ball bearings (90, 100) having different inside diameters and different outside diameters and same size balls. The bearings have different resonant frequencies whereby resonant noise does not compound. The cover (10) and base (12) are preferably made of cast magnesium alloy with the cover being convex configured for added strength.
Abstract:
A quadrature based embedded servo control system is provided to realize a high track density, high-performance hard disk drive system (10). Each data sector includes a gray code field spanning the entire width of the data track and a quad-servo burst pattern having first, second, third, and fourth servo burst fields distributed along the length of a portion of the data sector. The center point of the first, second, third, and fourth servo bursts are sequentially offset from the adjacent burst by a radial distance equivalent to one-half of the data track width. The quad-servo burst pattern is used with a track-following algorithm based on the quadrature value of (A + B) - (C + D) to obtain a substantially increased servo lock range. A second gray code field extending substantially the width of the data track and second quad-servo burst pattern substantially identical to the first is provided near a mid-point in the data portion of the data sector to increase the servoing information sample rate and accuracy, thereby permitting substantially increased data track densities to be utilized.
Abstract:
A read channel is described for use in a storage device including a storage medium (22a-d) for storing data, an interactive element (24a-h) for reading information from and writing information on the storage medium (22a-d) and a processor (35) for performing control functions in the storage device. The read channel comprises a set of electronic components (50, 52, 54) for receiving and processing information read by the interactive element from the storage medium. An adjustable noise generator (56) is included in the read channel and is coupled to the set of electronic components. The noise generator (56) is selectively operated to introduce noise into the set of electronic components to cause the set of electronic components to operate at a marginal level of performance and thereby increase the error rate of the read channel. A calibration of the read channel is performed when the read channel is operating at the marginal level of performance to decrease the time required to accumulate error statistics used in the calibration.