Abstract: A two-dimensional parity method and system for rotating parity information in a disk array, such as a RAID, to provide multiple disk fault tolerance with reduced write bottlenecks, is presented. The method includes forming a plurality of blocks, each block comprising a plurality of stripes extending across multiple disks, reserving at least one stripe in each block for parity, dividing each block into a plurality of chunks, wherein at least one of the chunks in the block comprises parity information, and shifting the position of each parity chunk in each block to a different disk with respect to the parity chunk in adjacent blocks. The method further includes shifting the position of each parity strip in the at least one stripe in each block to a different disk with respect to the parity chunk in adjacent blocks. A system for translating information in a disk array includes an array controller configured to shift parity chunks and parity strips.

Abstract: A system and method for providing multiple disk fault tolerance in an N-column by R-row logical representation of stored elements in an array of N independent disks, R minus 1 being less than N divided by a number of disk failures F, includes assigning each strip containing data to at least F different parity groups so that each strip containing data in a respective column is assigned to parity groups different than other strips containing data in the column. The method also includes calculating, for each parity group, a parity value corresponding to all of the strips assigned to the parity group. The method further includes storing each of the parity values in strips of different columns, so that none of the strips containing data in a column are assigned to a parity group for which the parity value for the parity group is stored in the column.

Abstract: A RAID 6 architecture including a disk array having a prime number minus 1 disks. A method of providing multiple disk fault tolerance in an N?column×R?row logical representation of a set of data elements, wherein N represents the number of disks in the array and R is equivalent to N/2, includes assigning each strip containing data to at least two different parity groups so that each strip containing data in a respective column is assigned to parity groups different than other strips containing data in the column. The method also includes calculating, for each parity group, a parity value corresponding to all of the strips assigned to the parity group. The method further includes storing each of the parity values in strips of different columns, so that none of the strips containing data in a column are assigned to a parity group for which the parity value for the parity group is stored in the column.

Abstract: A two-dimensional parity method and system that provides four-disk fault tolerance in an array of disks, such as a RAID system, is presented. The method includes arranging strips containing data in the disk array into horizontal, diagonal, and stepped parity sets, each parity set including at least one data strip as a member and no single data strip is repeated in any one parity set. The horizontal, diagonal, and stepped parities are than stored in respective disks and stripes of the array. In the event of up to a four simultaneous disk failures, lost data can be reconstructed by using the corresponding stored horizontal, diagonal, and stepped parity information and the data stored on the remaining intact disks.

Abstract: A two-dimensional parity method and system that provides five-disk fault tolerance in an array of disks, such as a RAID system. In an N×M logical representation of data in an array of disks, the method includes arranging strips containing data into two groups of stepped parity sets, the first group organized in a stepped configuration proceeding in one generally diagonal direction, the second group organized in a stepped configuration proceeding in another generally diagonal direction. Parites for respective parity sets in each group are calculated and stored in respective disks and stripes of the array. The method also includes arranging strips into horizontal and diagonal parity sets. In the event of up to five simultaneous disk failures, lost data can be reconstructed by using the corresponding stored horizontal, diagonal, and stepped parity information and the data stored on the remaining intact disks.

Abstract: A system and method for providing multiple disk fault tolerance in an N-column by R-row logical representation of stored elements in an array of N independent disks, R minus 1 being less than N divided by a number of disk failures F, includes assigning each strip containing data to at least F different parity groups so that each strip containing data in a respective column is assigned to parity groups different than other strips containing data in the column. The method also includes calculating, for each parity group, a parity value corresponding to all of the strips assigned to the parity group. The method further includes storing each of the parity values in strips of different columns, so that none of the strips containing data in a column are assigned to a parity group for which the parity value for the parity group is stored in the column.

Abstract: A two-dimensional parity method and system that provides two-disk fault tolerance in an array of disks, such as a RAID system, is presented. The method includes arranging strips containing data in the disk array into horizontal and diagonal parity sets, each parity set including at least one data strip as a member and no single data strip is repeated in any one parity set. Horizontal XOR parities are calculated for each horizontal parity set and stored in a designated disk. Diagonal XOR parities are calculated for each diagonal parity set and at least some of the diagonal XOR parities are stored in a designated disk. The remaining diagonal parities are stored in a corresponding strip in a diagonal parity stripe so that no members of a contributing diagonal parity set have the same disk index as the disk index of the corresponding strip of the diagonal parity stripe.

Abstract: A two-dimensional parity method and system that provides three-disk fault tolerance in an array of disks, such as a RAID system, is presented. The method includes arranging strips containing data in the disk array into horizontal and diagonal parity sets, each parity set including at least one data strip as a member and no single data strip is repeated in any one parity set. The diagonal parity sets are then grouped into two groups of diagonal parity sets—Group 1 and Group 2—such that each data strip is a member of a unique diagonal parity set in Group 1 and a unique diagonal parity set in Group 2. Horizontal XOR parities are calculated and stored in a designated disk. Diagonal XOR parities are calculated and at least some of the diagonal XOR parities are stored in a designated disk. The remaining diagonal parities are stored in a diagonal parity stripe so that diagonal parity can be retrieved in the event of a disk failure.

Abstract: A two-dimensional parity method and system that provides two-disk fault tolerance in an array of disks, such as a RAID system, is presented. The method includes arranging strips containing data in the disk array into horizontal and diagonal parity sets, each parity set including at least one data strip as a member and no single data strip is repeated in any one parity set. Horizontal XOR parities are calculated for each horizontal parity set and stored in a designated disk. Diagonal XOR parities are calculated for each diagonal parity set and at least some of the diagonal XOR parities are stored in a designated disk. The remaining diagonal parities are stored in a corresponding strip in a diagonal parity stripe so that no members of a contributing diagonal parity set have the same disk index as the disk index of the corresponding strip of the diagonal parity stripe.