Method of increasing the storage capacity of a level five RAID disk array by adding, in a single step, a new parity block and N--1 new data blocks which respectively reside in a new columns, where N is at least two

摘要

The storage capacity of a Level Five RAID array on an initial set of disks is expanded by the steps of: A) adding to the rows of the array, new data blocks but no parity blocks which reside on an additional set of disks; and, B) initializing the new data blocks such that the exclusive- or of their content in each row of the array is zero. Due to these steps A) and B), the need to rewrite the original data blocks and parity blocks on the initial set of disks as part of the expansion process is eliminated, and thus the expansion of the array occurs quickly. Alternatively, the storage capacity of a Level Five RAID array on an initial set of disks is expanded by the steps of: A) changing a parity block to a data block in a particular row on the initial set of disks, without altering the content of the changed block; B) adding in that particular row, one new parity block and N-1 new data blocks which reside on an additional set of N disks; and, C) initializing that new parity block and new data blocks such that the exclusive-or of their content is zero. By these steps A-C, the need to rewrite the original data blocks and parity blocks on the initial set of disks is again eliminated; and further the additional set of disks contains a parity block as well as data blocks.