Hitachi, Ltd.

Hitachi Global Storage Technologies Netherlands B.v.

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Video and Information System, Inc.

Yoshiju Watanabe

Seiichi Mita

Terumi Takashi

Naoki Satoh

Akihiko Hirano

Yasutaka Nishida

Yasuyuki Ito

Tatsuya Hirai

Shoichi Miyazawa

Yasuhide Ouchi

Ryushi Shimokawa

Toshio Kakihara

Yosuke Hori

Toshihiro Nitta

Koji Shida

Hideki Miyasaka

Tomoaki Hirai

Satoshi Minoshima

Koichi Arai

Hiroshi Ide

Morishi Izumita

Hideaki Maeda

Takashi Nara

Yuzo Nakagawa

Takushi Nishiya

Masaharu Kondo

Yoshiteru Ishida

Yoichi Uehara

Yasuyuki Itou

Kyoko Tsukano

A method for writing data to a disk drive. The method includes: receiving a write command; and, determining whether a beginning and an end of a rewrite area specified by the write command agree with boundaries of large-sized data sectors on a disk. The method also includes: reading head and tail data sectors and making a backup of the head and tail data sectors in first and second non-volatile memory areas, respectively, if the beginning of the rewrite area does not agree with the boundaries. The method includes starting a rewrite of the rewrite area after completing backups into first and second non-volatile memory areas. Moreover, the method includes: determining a state stage by using data in first, second, third and fourth non-volatile memory areas if a power shut-down occurs during execution of the write command; and, executing a recovery process in accordance with the determined state stage.

Disk drive including a host interface supporting different sizes of data sectors and method for writing data thereto

Embodiments of the present invention help to securely manage a data cryptographic key in a data storage device. In an embodiment of the present invention, a cryptographic processor for encrypting and decrypting data is located between a host interface and a memory manager. In parts of the hard disk drive (HDD), except for the host interface, the HDD handles user data in an encrypted state. A data cryptographic key which the cryptographic processor uses to encrypt and decrypt the user data is encrypted and stored in a magnetic disk. A multiprocessing unit (MPU) decrypts the data cryptographic key using a password and a random number to supply it to the cryptographic processor. Using the password and the random number, the HDD can manage the data cryptographic key with more security.

Data storage device and management method of cryptographic key thereof

A magnetic disk drive is provided capable of reducing a processing load even in a mode of, for example, reproduction during recording. In one embodiment, a magnetic disk drive includes a storage unit for storing certificate information that relates to the magnetic disk drive and corresponds to a root key of a certification organization. The certificate information is used on the host side to perform authentication processing of the magnetic disk drive.

Hard disk drive with certification function

Embodiments of the invention increase the convenience of a magnetic disk drive for portable use by shortening a period of time required to record a large amount of data, and by increasing the reproduction time, in the magnetic disk drive. In one embodiment, an area between servo data parts is interpolated by servo data parts, each of which stores a burst signal, so that the allocation density of a burst signal is made k times. At the time of write operation in which data is written, only the servo data parts are made use of to perform the servo control while a disk is driven at high rotational speed so as to reduce the recording time. At the time of read operation in which data is reproduced, the servo data parts are made use of to ensure the required precision of the servo control at low rotational speed that is 1/k of the rotational speed at the time of write operation. The reproduction at low rotational speed enables the reduction in power consumption.

Magnetic disk drive and magnetic disk medium

Embodiments of the invention allow relatively simple circuits to provide a coding device capable of coding longer bit-length data suitably for disk apparatus and a decoding device capable of decoding the data coded by the coding device. In one embodiment, a coding device comprises: a coder which, based on an M bits code string, produces an (M+1) bits coded string where each of the plural bits which may appear in the M bits code string is limited in run length; a preprocessor which produces an M bits code string by removing (N&#x2212;M) bits respectively from predefined (N&#x2212;M) positions of an incoming N bits code string and outputs the M bits code string to the coder; and a postprocessor which produces and outputs an (N+1) bits code string by inserting the (N&#x2212;M) bits, which are removed by the preprocessor, into predefined (N&#x2212;M) respective insertion positions of the (M+1) bits coded string output from the coder.

Coding device and decoding device

A data discriminating unit includes a data discriminator and a sync signal discriminator. A data sync signal is detected for the bit string discriminated from the output of the sync signal discriminator, and the data is demodulated for the bit string discriminated from the output of the data discriminator, thereby optimizing the signal to a form suitable for discrimination and detection of the data sync signal and demodulation for data reproduction. As a result, the detection performance of the data sync signal can be improved while maintaining the data discrimination performance. A Viterbi decoder is used for discrimination by the data discriminator and the sync signal discriminator for the optimization thereby to optimize the number of states, the number of paths for state transition and the path memory length. A signal having no continuous inversions of the recording data is used as the data sync signal.

Data synchronizing signal detector, signal processing device using the detector, information recording and reproducing apparatus having the detector and the device, data synchronizing signal detecting method, and information recording medium for using in the method

In a coding method which does not restrict a run length of '1' while data is recorded/reproduced, there are such a drawback that when an error correction is carried out, a total number of error data to be corrected is increased, and also errors of not-detectable data are increased. While data is coded, a continuous number of '1' contained in a code word is limited, and then an error correction is carried out inside a coding/decoding process operation. Thus, a recording/reproducing apparatus having a small number of decoding errors is available.

Decoding apparatus and decoding method

A data sync signal detecting device for detecting a sync signal having sync signal detection errors. The detecting device applies the output data of a most-likelihood decoder to shift register bit cells. The data is sequentially shifted and held in the bit cells of the shift register. The bit cell outputs are separated into odd-numbered and even-numbered bit string and applied to first and second pattern matching circuits. The odd-numbered bit string is matched with '01001' by a first pattern matching circuit. The even-numbered bit string is matched with '01011' by a second pattern matching circuit. First and second matching results are applied to a coincidence number adder/majority decision circuit. When coincidence occurs, the matching result is &#x201c;1&#x201d;, and when non-coincidence occurs, the matching result is &#x201c;0&#x201d;. The coincidence number adder/majority decision circuit produces a sync signal detection output when the first or second matching result is &#x201c;1&#x201d;.

Data synchronizing signal detecting device

When an error requiring a retry operation occurs, information concerning the error is stored every time. The information includes a sector number (or beginning sector number and number of sectors), the content of the command; a write or read designation, and the number of the times of error occurrence in the sector (or number of the times of retry operation), for example. In the case of recording information, like the prior art, information to be written which is stored in a buffer memory is held as is. Since the information concerning an error requiring a retry operation is stored, even though that error occurs repeatedly, a write and/or read operation of the next executable command to another track is executed without immediately switching to the retry operation. Thus, other commands are executed between the occurrence of the error requiring a retry operation and actual execution of the retry operation.

Information recording and reproducing method and information recording and reproducing device

Data synchronization detection is provided between data identification and code demodulation in a data reproduction system, which performs data synchronization detection using code-modulated data. A specified bit pattern generated in a data codeword is calculated in each phase (bit), using a specified bit sequence pattern that is not generated in a specified phase of the data codeword. For example, a specified bit sequence pattern is generated only in a specified phase of the codeword. The positions of the data codeword partitions are thereby identified. Scrambling is then applied to the write data as required in order to ensure accurate synchronization detection.

Data synchronization detection device, information recording device, information reproduction device, information recording format, signal processing device, information recording and reproducing device, and information recording medium

Data synchronization detection is provided between data identification and code demodulation in a data reproduction system, which performs data synchronization detection using code-modulated data. A specified bit pattern generated in a data codeword is calculated in each phase (bit), using a specified bit sequence pattern that is not generated in a specified phase of the data codeword. For example, a specified bit sequence pattern is generated only in a specified phase of the codeword). The positions of the data codeword partitions are thereby identified. Scrambling is then applied to the write data as required in order to ensure accurate synchronization detection.

Data synchronization detection method, information recording method, and information reproduction method

In order to precisely detect latent defects where a data-synchronizing signal is to be stored despite changes in the rotation of an information storage medium, a region data detection is used during a defect detection mode that is longer in the back-and-forth direction than a data-synchronizing signal used during a normal operation mode. The data detection region may be increased by the amount of change in the rotation. Thus, latent defects that may, due to a change in the rotation of the storage medium, come into agreement with the position of a data-synchronizing signal utilized during a normal mode of operation may be reliably detected, maintaining a high precision by taking a change in the rotation of the storage medium into consideration.

Error detecting method and device, information storing and reproducing device and magnetic disk drive

The present invention enables recovery of data reading, even when thermal asperities or defective media will make it impossible to increase the number of retries or to read the data, occur in the AGC/PLL part. In a device for writing and reading information, when an error occurs in the region of the recording media where the AGC/PLL signal is written, and if that information is written continuously to several sectors, then data reading is performed by using the AGC/PLL of the following sector, without performing a retry, or by performing a minimum number of retries.

Signal processing technique for preventing delay in read time from retry operations

A signal processing circuit having a data sync signal detector and a disk device. Input data read from a magnetic disk is input to a data discriminator. A data discrimination output constituting a code bit output discriminated by the data discriminator is input to a post-coder the output of which is input to a decoder and a (1+D) processing unit. The processed output of the processing unit is input to an error detection/correction unit and separated into bit strings of odd numbered bits and even numbered bits, divided into groups. An error detection/correction output is input to a data sync signal detector, and matched against a sync pattern. When the number of coincident groups is greater than a threshold value, a sync signal is output and upon detection causes the decoder to demodulate the data.

Signal processing method and apparatus and disk device using the method and apparatus

When an error requiring a retry operation has occurred, information concerning the error requiring a retry operation is stored every time. The information includes a sector number (or beginning sector number and number of sectors), the content of the command; a write or read designation, and the number of the times of error occurrence in the sector (or number of the times of retry operation), for example. In case of recording information, like the prior art, information to be written which is stored in a buffer memory is held as it is. Since the information concerning an error requiring a retry operation is stored, even though an error requiring a retry operation occurs repeatedly, a write and/or read operation of the next executable command to another track is executed without immediately switching to the retry operation. Thus, other commands are executed between the occurrence of the error requiring a retry operation and actual execution of the retry operation.

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Ninomiya, Japan

Yoshiju Watanabe