Abstract: When parity checking in a disk array such as a RAID-6 system determines data and parity information is unsynchronized, additional calculations are performed to determine whether the error may be attributed to faulty data on a disk drive or to a more systemic problem such as a faulty controller. In particular, for each particular error detected, the parity generating information is analyzed to determine if each error involves a common disk index. If so, the data can be corrected on that disk; if not other corrective procedures are implemented.

Abstract: When parity checking in a disk array such as a RAID-6 system determines data and parity information is unsynchronized, additional calculations are performed to determine whether the error may be attributed to faulty data on a disk drive or to a more systemic problem such as a faulty controller. In particular, for each particular error detected, the parity generating information is analyzed to determine if each error involves a common disk index. If so, the data can be corrected on that disk; if not other corrective procedures are implemented.

Abstract: In a disk array environment such as a Redundant Array of Independent Disks-6 (RAID-6) environment, the overall performance overhead associated with exposed mode operations such as resynchronization, rebuild and exposed mode read operations is reduced through increased parallelism. By selecting only subsets of the possible disks required to solve a parity stripe equation for a particular parity stripe, accesses to one or more disks in a disk array may be omitted, thus freeing the omitted disks to perform other disk accesses. In addition, disk accesses associated with different parity stripes may be overlapped such that the retrieval of data necessary for restoring data for one parity stripe is performed concurrently with the storage of restored data for another parity stripe.

Abstract: Data associated with the state of a parity update operation in a disk array system such as a RAID-6 system is stored during performance of the operation so that, in the event the operation is interrupted, recovery may be initiated using the stored data. The stored data may include a state indicator that is indicative of the status of the parity update operation, and snapshot data (e.g., a delta value indicative of a difference between new and old data) captured during the parity update operation.

Abstract: When parity checking in a disk array such as a RAID-6 system determines data and parity information is unsynchronized, additional calculations are performed to determine whether the error may be attributed to faulty data on a disk drive or to a more systemic problem such as a faulty controller. In particular, for each particular error detected, the parity generating information is analyzed to determine if each error involves a common disk index. If so, the data can be corrected on that disk; if not other corrective procedures are implemented.

Abstract: When parity checking in a disk array such as a RAID-6 system determines data and parity information is unsynchronized, additional calculations are performed to determine whether the error may be attributed to faulty data on a disk drive or to a more systemic problem such as a faulty controller. In particular, for each particular error detected, the parity generating information is analyzed to determine if each error involves a common disk index. If so, the data can be corrected on that disk; if not other corrective procedures are implemented.

Abstract: Data associated with the state of a parity update operation in a disk array system such as a RAID-6 system is stored during performance of the operation so that, in the event the operation is interrupted, recovery may be initiated using the stored data. The stored data may include a state indicator that is indicative of the status of the parity update operation, and snapshot data (e.g., a delta value indicative of a difference between new and old data) captured during the parity update operation.

Abstract: Data associated with the state of a parity update operation in a disk array system such as a RAID-6 system is stored during performance of the operation so that, in the event the operation is interrupted, recovery may be initiated using the stored data. The stored data may include a state indicator that is indicative of the status of the parity update operation, and snapshot data (e.g., a delta value indicative of a difference between new and old data) captured during the parity update operation.

Abstract: When parity checking in a disk array such as a RAID-6 system determines data and parity information is unsynchronized, additional calculations are performed to determine whether the error may be attributed to faulty data on a disk drive or to a more systemic problem such as a faulty controller. In particular, for each particular error detected, the parity generating information is analyzed to determine if each error involves a common disk index. If so, the data can be corrected on that disk; if not other corrective procedures are implemented.

Abstract: During a parity update of a parity stripe in a disk array, constant values used in finite field arithmetic are algebraically combined in order to reduce the number of buffers and steps needed to update multiple parity values when a change in data occurs. In one implementation, for example, the contents of a buffer that stores the product of a delta value associated with the change in data and a first constant, which is used to update a first parity value, are multiplied by a value representative of the ratio of a second constant, which is used to update a second parity value, and the first constant.

Abstract: A method for maintaining data coherency in a dual Input/Output(I/O) adapter having primary and secondary adapters, wherein each of the primary and secondary adapters includes resident write cache data and directory storage devices. The method includes utilizing a split point to separate each of the cache data and directory storage devices into first and second regions, wherein the first regions contain the primary adapter cache data and directory information and the second regions contain the secondary adapter cache data and directory information. Information stored in the primary adapter cache data and directory storage devices is mirrored into the secondary adapter cache data and directory storage devices or, alternatively, information stored in the secondary adapter cache data and directory storage devices is mirrored into the primary adapter cache data and directory storage devices utilizing a dedicated communication link, such as a high-speed serial bus, between the primary and secondary adapters.

Abstract: A method for maintaining data coherency in a dual Input/Output(I/O) adapter having primary and secondary adapters, wherein each of the primary and secondary adapters includes resident write cache data and directory storage devices. The method includes utilizing a split point to separate each of the cache data and directory storage devices into first and second regions, wherein the first regions contain the primary adapter cache data and directory information and the second regions contain the secondary adapter cache data and directory information. Information stored in the primary adapter cache data and directory storage devices is mirrored into the secondary adapter cache data and directory storage devices or, alternatively, information stored in the secondary adapter cache data and directory storage devices is mirrored into the primary adapter cache data and directory storage devices utilizing a dedicated communication link, such as a high-speed serial bus, between the primary and secondary adapters.