Patent ID: 7103716
Filing Date: 2006-09-05
Classification: G06F

Abstract:
1. In an N−column by R−row logical representation of a set of data elements in an array of independent disks, N being equal to one less than a prime number P, and R being equal to half of one less than P, the data in the set organized into a plurality of stripes, each stripe comprising a plurality of strips, all strips of a column located on the same disk, and one and only one parity value stored per column per a reconstruction set, a method of providing multiple disk fault tolerance comprising: 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 same column, wherein assigning each strip containing data to at least two different parity groups comprises assigning membership in a first parity group, GA where r indicates the current row location of the strip containing data, c represents the current column location of the strip containing data, x represents the multiplication function, and P is equal to the number of disks in the array +1; and assigning membership in a second parity group GB where r indicates the current row location of the strip containing data, c represents the current column location of the strip containing data; N represents the number of disks in the array, x represents the multiplication function; and P is equal to N+1; calculating, for each parity group, a parity value corresponding to all of the strips assigned to the parity group; and 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 whose parity value is stored in that column.