Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Palo Alto Networks, Inc.

Zhi Ning Wang

Jenghung Chen

David Dung Tien Nguyen

Jr-Yi Shen

Min Chen

Anupam Bharali

Jianghong Ding

Kunal Kundu

Chun Sei Tsai

Duc T Phan

Carl E Barlow

Robert J McNab

Kenny T Coker

Hemant Melkote

Hien T Chu

Bang X Phan

Jenghung Cheng

Deploying policy configuration across multiple security devices through hierarchical configuration templates is disclosed. In some embodiments, deploying policy configuration across multiple security devices through hierarchical configuration templates for configuring a plurality of security devices includes receiving at a first security device a hierarchy of templates from a central management server, in which the hierarchy of templates includes configuration information for a group of security devices, and in which the first security device is included in the group of security devices; and reconciling on the first security device's configuration information included in the hierarchy of templates and device specific configuration based on local configuration information, in which the first security device performs an object level reconciliation to maintain device configuration consistency.

Deploying policy configuration across multiple security devices through hierarchical configuration templates

A method is disclosed for adaptive learning of fundamental-frequency repeatable runout (1FRRO) compensation information in a disk drive. The disk drive includes a transducer head, a magnetic disk having a plurality of concentric data tracks defined by embedded servo wedges that provide position information, and a control system. In the method, 1FRRO compensation information is learned over a predetermined minimum number of disk revolutions. After the predetermined minimum number of disk revolutions, the 1FRRO compensation information is monitored for convergence while learning of the 1FRRO compensation information continues. Learning is terminated upon detection of convergence of the 1FRRO compensation information.

Method for improved repeatable runout learning in a disk drive

Harmonic selection for track following is described for a hard disk drive comprising at least one magnetic disk capable of storing data and spinning, a controller capable of controlling a read/write head capable of reading and writing data while following a track on a surface of the at least one magnetic disk, and a memory device capable of storing data relating to the operation of the hard disk drive. A drive function test on the hard disk drive is performed, during which harmonic frequencies are identified which cause disturbances for the hard disk drive. Data regarding the harmonic frequencies which cause the greatest disturbances for the hard disk drive is stored in the memory device. The data regarding the harmonic frequencies which cause the greatest disturbances is forwarded to the controller upon the at least one magnetic disk spinning.

Harmonic selection for track following on a hard disk drive

Unequal zoning for track following on a hard disk drive comprising at least one magnetic disk, a read/write head connected to at least one actuator arm and capable of reading and writing data on said at least one magnetic disk, a controller capable of moving said at least one actuator arm. A track is followed using the read/write head on the surface of the at least one magnetic disk. Information is stored at the controller regarding off-track displacement of the read/write head. A plurality of unequal zone partitions is created, wherein an unequal zone partition of the plurality of unequal zone partitions represents a physical region of the at least one magnetic disk and wherein the plurality of unequal zone partitions are based on the information regarding the off-track displacement of the track and are used by the controller to compensate for the off-track displacement of the track.

Unequal zoning for track following on a hard disk drive

A method for controlling the effects of seek-induced vibration of a component part in a hard-disk drive. The method includes determining a resonant frequency of seek-induced vibration of the component part and a reference amplitude of a frequency-component in a first voice-coil-motor signal (VCMS) at the resonant frequency. The method also includes synthesizing a second VCMS with an amplitude of a frequency-component attenuated below the reference amplitude of the frequency-component in the first VCMS at a frequency in a resonance-band bracketing the resonant frequency. The method also includes driving a voice-coil of a voice-coil motor with the second VCMS to reduce an amplitude of a frequency-component at the resonant frequency in a second PES of the seek of the data track associated with the second VCMS below a reference amplitude of a frequency-component at the resonant frequency in the first PES associated with the first VCMS.

Method and apparatus for controlling the effects of seek-induced vibration of a component part in a hard-disk drive

A disk drive comprising a moveable head, a disk, and a servo controller that implements servo control techniques to preserve PES continuity during track following operations is disclosed. The disk includes a plurality of tracks in which a substantial majority of the tracks include a plurality of servo sectors having a plurality of servo bursts that are utilized in track following operations. The servo controller controls track following operations with the moveable head and implements operations to preserve PES continuity during track following. These operations include: dividing tracks of the disk into a plurality of zones wherein each zone includes zone boundaries; and utilizing a PES equation for each zone to generate a PES value based upon read servo bursts wherein each zone PES equation includes a normalizing factor to account for boundary conditions associated with zone boundaries to preserve PES value continuity between zones.

Disk drive servo control techniques to preserve PES continuity

Disclosed is a disk drive and method to characterize misaligned servo wedges. The disk drive includes an actuator arm, a head, a disk, and a servo controller. The head is connected to a distal end of the actuator arm in which the actuator arm is rotatable about a pivot to move the head radially over the disk. The servo controller is used to characterize misaligned servo wedges by implementing operations including: commanding the head to track follow on a track; measuring wedge-to-wedge time (WTWT) values corresponding to time intervals between identified servo wedges; calculating wedge-to-wedge time (WTWT) variations for the measured WTWT values; and characterizing the calculated WTWT variations, wherein, characterizing the calculated WTWT variations for the track includes utilizing a WTWT variation modeling function to model the WTWT variations.

Disk drive to characterize misaligned servo wedges

Disclosed is disk drive comprising an actuator including a head, a disk having a plurality of tracks, and a processor to control the movement of the actuator and the head relative to the disk. The processor is coupled to the actuator by a flex circuit cable. The processor commands the application of a pre-calibrated bias signal to the actuator during an idle mode to compensate for a bias force imparted by the flex circuit cable upon the actuator such that the head is maintained proximate a pre-determined track of the disk within a pre-determined idle zone of tracks and further determines if a back electromagnetic force (BEMF) reading associated with the actuator is greater than the threshold value, and if so, commands an exit out of the idle mode.

Disk drive idle mode responsive to flex circuit cable bias changes

A method is disclosed for efficiently determining and writing repeatable runout (RRO) compensation value sets for data tracks on a magnetic disk in a disk drive. The disk drive has a magnetoresistive (MR) head having a read element and a separate write element, and a secondary actuator coupled to the end of a primary actuator for adjusting a head skew angle. In the method, the head skew angle is set such that the read and write elements are substantially aligned along the first track. A position error signal for each servo sector is determined over a predetermined number of disk revolutions during track following along a first data track. An RRO compensation value set is calculated for the first data track based on the position error signals. The RRO compensation value set is written for the first data track. A seek operation is then performed to a second data track.

Magnetic disk drive and method for efficiently determining and storing RRO compensation values using a secondary micro-actuator

A disk drive is disclosed including a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors. The disk drive further comprises a head coupled to a distal end of an actuator arm, and a voice coil motor (VCM) comprising a voice coil for rotating the actuator arm about a pivot. A read command is selected from a command queue, wherein the read command comprises a requested data sector. A maximum number of additional data sectors is determined that may be cached together with the requested data sector. An actual number of additional data sectors to cache is selected in response to the maximum number and a temperature of the voice coil.

Disk drive adjusting predictive caching based on temperature of voice coil motor

A method is disclosed for determining fundamental-frequency repeatable runout (1FRRO) coefficients in a disk drive. The disk drive includes a transducer head, a rotating magnetic disk having a plurality of concentric data tracks defined by embedded servo wedges that provide position information, and an actuator coupled to the head. In the method, the head is caused to move in a substantially constant velocity motion across a selected portion of the tracks of the rotating magnetic disk in response to a control signal. The position information is read from the embedded servo wedges as the head moves across of the selected portion of the tracks. The 1FRRO coefficients are determined based on the position information read as the head moved in a substantially constant velocity motion across the selected portion of the tracks.

Method for improved repeatable run out learning in a disk drive

A disk drive is disclosed including a disk having a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors forming N servo wedges, and a wedge time period (WTP) occurs between each servo wedge. A VCM control signal is generated by generating an estimated WTP by detecting the servo sectors, estimating a pivot velocity in response to the estimated WTP, the pivot velocity representing a velocity of an actuator arm about a pivot, generating a pivot friction compensation in response to the estimated pivot velocity, and generating the VCM control signal in response to the pivot friction compensation.

Disk drive employing pivot friction compensation

A disk drive is disclosed comprising a voice coil motor (VCM) for rotating an actuator arm about a pivot in order to actuate a head over a disk. The disk is rotated by a spindle motor, and a feed-forward compensation value is computed that compensate for a non-centric alignment of the disk with respect to the spindle motor. During a calibration mode, the VCM is controlled to press the actuator arm against a crash stop, and the feed-forward compensation value is computed in response to a position error signal (PES). The PES is generated in response to embedded servo sectors recorded on the disk, wherein each embedded servo sector comprises a track address for coarse alignment and servo bursts for fine alignment.

Disk drive computing repeatable run out while actuator arm is pressed against crash stop

A disk drive is disclosed that estimates a sinusoidal error in a wedge time period due to eccentricity in the disk rotating to generate eccentricity compensation values. During a write operation a head is positioned over a target data sector within a target track, a write clock frequency is set using an eccentricity compensation value corresponding to the target data sector, and data is written to the target data sector using the write clock frequency. In this manner, the eccentricity compensation value adjusts the write clock frequency to better optimize the linear bit density from the inner to outer diameter tracks.

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San Jose, CA, United States of America

Zhi Ning Wang