Patent ID: 6453428
Filing Date: 2002-09-17
Classification: G06F

Abstract:
A method for assigning data chunks to column parity sets in a dual-drive fault tolerant storage disk drive system having N disk drives, where N is a prime number, the method comprising the operations of:a) organizing each of the N disk drives into N chunks such that the N disk drives are configured as one or more NÃ—N arrays, each of the arrays having chunks arranged in N rows from row 1 to row N and in N columns from column 1 to column N, each row including a plurality of data chunks for storing data and a column parity chunk for storing a column parity set, each row of the array further including a row parity chunk for storing a row parity set and wherein the data chunks in each row are assigned to the row parity set, each column parity set being associated with a set of data chunks in each of the arrays, wherein row m is associated with column parity set Qm where m is an integer that ranges from 1 to N; b) for row 1 of a selected NÃ—N array, b1) assigning a first data chunk to a column parity set Qi, wherein i is an integer determined by rounding down (N/2); and b2) for each of the remaining data chunks, assigning each data chunk to a column parity set Qj, wherein j is an integer one less than a column parity set for the preceding data chunk and wherein j wraps to N when j is equal to 0; and c) for each of the remaining rows 2 to N of the selected array, c1) assigning a first logical data chunk to a column parity set Qk, wherein k is one greater than the column parity set for the first logical data chunk in a preceding row and wherein k wraps to 1 when k is equal to (N+1); and c2) for each of the remaining data chunks, assigning each data chunk to a column parity set Qn, wherein n is an integer one less than a column parity set for the preceding data chunk and wherein n wraps to N when n is equal to 0.