Abstract: A method of and an apparatus for duplicating direct access storage devices (DASDs) such as hard disk drives (HDDs). The apparatus includes a portable HDD duplicator which can be connected to an existing personal computer (PC), and perform fast data duplication directly from a source HDD to a multiplicity of target HDDs simultaneously. The method includes the steps of providing direct data paths between the source HDD and the target HDDs and performing high speed data duplication and comparison functions by reading the source HDD and writing to the target HDDs at the same time.

Abstract: A system and method for updating data. A first processing unit, such as an adaptor, receives a data update to a data block in a first storage device, such as a hard disk drive. Parity data for the data block is maintained in a second storage device, e.g., another hard disk drive. A parity group is comprised of the data block and corresponding parity data. The first processing unit determines whether the first processing unit controls access to the parity group, i.e., the state of lock ownership. The first processing unit transmits the data update to a second processing unit after determining that the first processing unit does not control access to the parity group. The second processing unit, another adaptor, performs an update after receiving the data update from the first processing unit. The first processing unit performs an update after determining that the first processing unit controls access to the parity group.

Abstract: A method is provided for reducing the number of transactions for multi-segmented host system write operations in a RAID 6 device. The method comprises sending a write command for new multiple data segments to a plurality of data drives in the RAID 6 device via a RAID 6 controller. The RAID 6 device has data segments stored in stripes on the data drives and parity drives within the RAID 6 device. Parity is calculated for old data segments, new data segments and old parity on the parity drives to determine a new parity. The new parity is then written to one parity drive of the multiple parity drives within the RAID 6 device, thereby reducing the number of read and write transactions between the controller and the drives within the RAID 6 device.

Abstract: A cost reduced finite field processor is disclosed for computing the logarithm LOG.sub..alpha. (.alpha..sup.j) of an element of a finite field GF(2.sup.n) using significantly less circuitry than that required by a lookup table typically employed in the prior art. The result of the logarithm (i.e., the exponent of .alpha..sup.j) is represented as a binary number computed serially one bit per clock cycle. In one embodiment, combinatorial logic is used to compute bit 0 of the exponent. On each clock cycle, the exponent is shifted once to the right and bit of the exponent is extracted until the entire exponent has been computed. Shifting the exponent of a field element to the right is carried out by taking the square root of the element. The present invention requires at most n+1 clock cycles to compute LOG.sub..alpha. (.alpha..sup.j), with one embodiment requiring n/2 clock cycles.

Abstract: A disk data reproducing apparatus and a disk data reproducing method for carrying out error correction at fixed intervals independent of demodulation rate fluctuations caused by variable disk revolutions during access, whereby the reliability of error correction is improved. Data are demodulated by use of a regenerative clock signal acquired in keeping with the input data rate, whereas error correction is conducted at a fixed frequency clock signal. Two counters are provided, one being incremented by a signal generated upon detection of a block top, the other counter being incremented by a signal generated when a block of erroneous data is corrected. The two computers are compared in contents so that depending on the result of the comparison, an error correction start signal is generated. Error correction is performed always at fixed intervals regardless of the velocity of reproduction being standard, doubled, quadrupled, or multiplied by a factor of j (j: natural number).

Abstract: There is provided a disc array control method and apparatus for controlling access to a disc drive consisting of a plurality of second data obtained by dividing a first data and a plurality of discs for storing the error correction data for the second data. Particularly, the disc array control method and apparatus of the present invention determines the information consisting of disc storing a plurality of the second data and address on the disc, data size of a plurality of second data and disc storing the error correction data and address on the disc to make equal the time required for access to a plurality of second data and error correction data and executes the access to the disc drive on the basis of the determined information. Thereby, the time required for access to the error correction data and sub-blocks can be set to equal time and the real-time property can be assured while maintaining high reliability.

Abstract: Apparatus and methods for storing predefined information with error correcting code (ECC) in a direct access storage device are provided. Predetermined information is identified and loaded to an ECC generator for customer data to be read and written. The identified predetermined information includes an address for customer data to be read and written. The customer data is written and loaded in parallel to the ECC generator. Then the generated ECC that reflects the pre-loaded predetermined information is written at the end of the written customer data. The customer data and ECC is read and loaded in parallel to the ECC generator. Errors in the predetermined information that is not written to the disk surface, can be detected from the read ECC.

Abstract: A Redundant Array of Independent Disks (RAID) system that is adaptable to host Input/Output traffic, wherein the RAID configuration is hidden from the host computer, and wherein the system uses various methods for striping and organizing data across the array when disks are added or removed. The system dynamically determines the RAID configuration used to store host data. To maximize response time and avoid a write penalty, small write operations are mapped into RAID 1 configurations, and medium and large write operations are mapped into RAID 3 configurations. The data are migrated into RAID 5 configurations as a background operation, to minimize the disk space lost. The system hides configuration changes necessary for the addition and/or removal of disks to/from the disk array by unstriping data, adding or deleting (removing) a disk and then restriping data over all the disks.

Abstract: An on-chip testing device separately locates must-repairs or preferred-repairs in a row direction and column direction of a memory array. A row counter and a column counter are operated to index the memory array in row-major order, and then in column-major order (or vice versa). A running total of the number of failures is kept for each row and column, when the running total equals or exceeds a predetermined value, the row or column is determined to be a must-repair or a preferred repair.

Abstract: A redundant array storage system in which a reserved area of a multiplicity of data storage units can be reliably synchronized, even if the synchronization cycle is interrupted by an unforeseen event or situation, such as sudden loss of power to the system or a component failure. By maintaining two groups or partitions of data storage units and updating only one group at a time, and by having a global table which provides information regarding which group of storage units is being updated, the present invention allows the system to reliably determine which of the data storage units maintain valid data in their reserved area and to conform the reserved areas of the other group of data storage units to the valid values, without the use of additional hardware devices.

Abstract: The present invention relates to a disc array apparatus assuring that even if contradiction is detected in matching of parity data during a read parity check, correct host data is Restructured and can always be transferred to the host. The disc array apparatus of the present invention is particularly applicable to disc drives in the RAID configuration. For example, in a disc array apparatus of the present invention implementing RAID level 3, the disc array apparatus adds CRC data to data transferred from a host computer, divides the data, generates parity from the divided data, and stores the data and the parity data into the disc drives. During a read operation, the disc array apparatus of the present invention executes a read parity check.

Abstract: In the event that during write to a storage device such as a DVD, data does not fill up a unit of generation of an error correction code (ECC), an increase in the data transfer amount caused by reading a shortage of data from a storage medium can be prevented. Controlling is carried out such that write data is not immediately written to the storage medium but write operation is deferred until an amount of data of ECC generation unit is complete in a buffer memory. As a result, the ECC can be generated and written to the storage medium by using only the write data without resort to read of the shortage of data from the storage medium.

Abstract: A quick retry operation is possible by outputting an error flag pertaining to a sector after error correction processing of digital data. When an output of an error detection flag unit for a correction block indicates the existence of an uncorrectable error, the sectors are checked to see if the sectors corresponding to retrieved data include any error or not based on output from a sector error flag register B. When the sectors are judged as error, signals are retrieved again from a storage medium, restored in a memory, and an error correction processing is repeated again. The data such as that of P pictures or B pictures of MPEG which can be reproduced even with errors are output even when the error detection flag unit indicates the existence of the uncorrectable error. It enables identification of the sectors with the errors and simplifies the following operations pertaining to the error at a data receiving side by outputting the error flag along with the data.

Abstract: In the read-write apparatus of the present invention, concentrated sliding of the read-write head in a specific area on the recording media is reduced. The recording media is rotationally set and the read-write head contacts the recording media to read and write information on the recording media. While the read-write head is accessing (read/write) the information on the recording media, a slide count calculation section calculates a slide count of the read-write head by monitoring the servo information of the recording media. The memory section stores the slide count calculated by the slide count calculation section by unit of access area. The relocation section suitably relocates the information recorded on the recording media in accordance with the slide count by unit of the access area.

Abstract: The invention provides a method and apparatus for increasing the efficiency of data transfer between a host computer and a disk array in a RAID system. The invention operates by splitting up large I/O requests from the computer into smaller, more manageable pieces and processing the pieces as though they were individual I/O requests. In one embodiment, the invention keeps only a limited number of these smaller individual I/O requests "active" at any particular time so that a single large I/O request cannot preclude other I/O requests from making progress in the controller. Both the size of the smaller I/O request pieces and the limited number of these pieces which will be "active" at any one time may be tunable parameters. The invention improves the efficiency of data transfer between the host computer and the array of disk drives by providing for increased overlap of activity in the controller. This increased overlap of activity results in increased controller throughput.

Abstract: A parity which is used to a disk array is formed by using a cache memory. A storing method of the cache memory is classified into three methods such that: only data is stored; only redundant information is stored; and both of the data and the redundant information are stored. Even when a power source is shut off during the data writing process, the processing stages of the data writing and parity updating and the necessary data are stored into a non-volatile memory and are used for recovery.

Abstract: The present invention provides a method and system for detecting corrupted data of a plurality of hard disk drives (HDDs) in a data storage subsystem. In this system a predetermined number of fixed blocks within each of the HDDs emulate a track of a first track format. The predetermined number of fixed blocks provide a logical track. The logical track of one of the plurality of HDDs is generated by the others of the plurality of HDDs. The plurality of logical tracks forming a plurality of track groups. In a first aspect the method and system comprises assigning each of the plurality of logical tracks an address translation (ADT) number, comparing each of the ADT numbers of the plurality of logical tracks to an expected value until a mismatch occurs in a logical track, and determining if other logical tracks in a same track group have accurate ADT numbers. The first aspect further includes reconstructing the logical track if the other tracks within the same track group have accurate ADT numbers.

Abstract: A system and method for reconstructing data, and/or generating a parity bit for use in reconstructing data, in a data storage system having a set of disk drives and an associated redundant disk drive. The system includes a memory having an exclusive OR gate to provide an accumulated exclusive ORing of the data successively coupled thereto. The accumulated exclusive OR result is coupled to the redundant disk drive in generating the parity bit or to a replaced disk drive when reconstructing data. The system includes: a bus; a controller coupled between the bus and the disk drives; an addressable memory coupled to the bus. The memory includes: a write buffer memory having an input coupled to the bus; a read buffer memory having an output coupled to the bus; and, the exclusive OR logic unit having a pair of inputs. One input is coupled to an output of the write buffer memory and another input is coupled to the output of the read buffer memory.