Seagate Technology Incorporated

Jpmorgan Chase Bank, As Collateral Agent

WeiLoon Ng

YongPeng Chng

Xiong Liu

Wenxiang Xie

Myint Ngwe

Beng Wee Quak

ChoonKiat Lim

UttHeng Kan

Joseph Cheng-Tsu Liu

BengWee Quak

KokHoe Chia

Kwee Teck Say

LeeLing Tan

CheeWai Lum

Wesley Chan

Aik Chuan Lim

Steven TianChye Cheok

QuekLeong Choo

Swee Kieong Choo

Patrick Tai Heng Wong

Kay Hee Tang

SweeKieong Choo

EngHock Lim

Wesley Wing Hung Chan

Chwee Fern Ee

Jeffrey Soon Beng Sim

YingEe Yip

Liza MuiCheng Chia

Method and apparatus for generating a random number, such as for use in a security protocol to control access to a data processing system. A processor generates the random number in relation to a back electromotive force (BEMF) value. The BEMF value is preferably obtained in response to application of current to a circuit. The circuit preferably comprises a coil and the application of current preferably induces a relatively small movement of the coil. The random number is preferably a multi-bit digital value, and each bit of the random number is determined in relation to whether the corresponding BEMF value is even or odd. The coil preferably comprises a coil of a voice coil motor (VCM) used to position a transducer adjacent a rotatable storage medium, and the random number is preferably generated while the medium is in a non-rotatable state.

Random number generation using back electromotive force (BEMF) values

True random numbers are generated from position error signals or like signals. The generator is not dependent on a potentially biased reference or threshold, and is capable of quickly generating true random numbers on demand. The present invention can be implemented as an integral functionality of a data storage device to control access to data stored in the data storage device. It can also be implemented in data storage devices for controlling access to host systems or host devices associated with the data storage devices.

True random number generation

A disc drive includes a transducer having a separate element for writing information and a separate element for reading information to and from the disc. In a disc drive designated to read and write long sequential records, the track misregistration budget is reduced to account for previously written tracks not being encroached on one side. An initial track is written. Subsequent tracks are written after a seek in one direction. The subsequent track is written so that the initially written track is overwritten to one side and leaves a track having a width substantially equal to the width of the read element. Records can be written into data bands of a selected number of tracks. A guard band is left between groups of data bands so that data on tracks in subsequent data bands are not overwritten.

Method to achieve higher track density by allowing only one-sided track encroachment

A method to improve drive read performance in a disc drive includes powering-up a disk drive, reading reassigned sectors data from a reassign spare pool, and storing the reassigned sectors data in a reassigned cache segment. This method also includes initiating a read request, detecting a reassigned sector within the read request, and determining whether the requested sector can be located in the reassignment cache. If the reassigned sectors are found in the cache, then the method includes transferring the reassigned sector data from the reassignment cache to the read buffer or directly to the requesting host computer. If the reassigned sectors are not found in the cache, then the method includes seeking to the reassignment spare pool to fetch as much reassigned sectors data as the reassignment cache can hold. In another embodiment, the reassigned sectors data stored in a reassignment cache segment is located in a buffer.

Caching data from a pool reassigned disk sectors

In one embodiment of the present invention, systems and methods are provided through which the capacity of a defect buffer in a microcontroller of a mass storage device is determined without regard for the quantity of defects on a recording medium. The capacity of the defect buffer is determined in varying examples, based on the amount of available buffer space and/or the application of the storage device. In one embodiment, the capacity of the defect buffer is less than the quantity of defects on the recording medium, wherein entries in a defect table on the recording medium are swapped in and out of the defect buffer as needed, such as using a most-recently-used scheme. In another embodiment of the present invention, systems and methods are provided through which the defect table is partitioned into a plurality of segments that are physically distributed throughout the recording medium.

System and method for adaptive storage and caching of a defect table

There is provided a method and system of maintaining partition information relating a computer disc drive. The method includes detecting partition information which is located in the first sector of a partition of a disc drive and determining if it is valid, and comparing the valid partition information with a corresponding duplicate of the partition information which is located in a reserved area. For valid partition information which is the same as the corresponding duplicate of the partition information, a standard booting procedure for the computer is allowed to continue. For valid partition information which is not the same as the corresponding duplicate partition information, valid partition information is stored in the reserved area. For partition information which is not valid, the invalid partition information is replaced with corresponding duplicate partition information which is valid.

Partition recovery method

An apparatus and associated method for detecting head collision with disc media, or other matter, during a write operation is disclosed. The method and apparatus generally monitor the resistance of an MR element on the head in order to detect a temperature increases indicative of a head collision. The resistance can be compared to a pre-selected threshold to generate an output indicative of head collision.

Write head collision detection using MR read element in disc drives

A method and apparatus for reducing retry redundancy during disc read operations in a disc drive system are provided in which a number of physical sectors to be read from the disc during read operations is first determined. An attempt is then made to read all sectors of the number of sectors during a first disc revolution. Failed sectors of the number of sectors during the first disc revolution are also identified. A retry cycle is then performed on the failed sectors during a second disc revolution following the completion of the attempt to read all sectors of the number of sectors during the first revolution.

Method and apparatus to reduce retry redundancy during read operations

A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes a defect management system for managing defective sectors located on the disc surface of a disc within the disc drive. The defect management system includes a controller, and a memory associated with said controller. The controller skips at least a first defective sector and a second defective sector. The first defective sector may be contiguous with the second defective sector or at least one writable sector is located between the first defective sector and the second defective sector. The controller also controls the head to write at least the last two sectors of the plurality of sectors to be written to at least two contiguous sectors located in a pool of spare sectors. A method for writing a plurality of sectors of information to a storage surface on a disc in a disc drive includes determining the start location for writing the plurality of sectors; and determining a number of skipped defective sectors that will be encountered when writing the plurality of sectors. At least two sectors of the plurality of sectors are reassigned and written to at least two sectors in a spare sector pool. The method includes storing the location of the spare sectors within the spare sector pool so that the spare sectors may be located at a subsequent time during a read operation.

On the fly defect slipping

According to one embodiment of the present invention a disc controller in a disc drive includes a cache memory and a control circuit. The control circuit is configured to identify an operating system of a host computer coupled to the disc drive, select a segmentation level for the cache memory based on the identified operating system, and store information in the cache memory according to the segmentation level. According to another embodiment of the present invention a cache memory in a disc drive is operated by identifying an operating system of a host computer coupled to the disc drive, selecting a segmentation level for the cache memory based on the identified operating system, and storing information in the cache memory according to the segmentation level. The operating system is identified by reading a partition type from a master boot record stored in a disc in the disc drive.

Adaptable cache for disc drive

Growing community of inventors

Singapore, Singapore

WeiLoon Ng