Concentrated parity technique for handling double failures and enabling storage of more than one parity block per stripe on a storage device of a storage array

摘要

A method for constructing an array of storage devices is disclosed. A number of storage devices is selected. Each storage device stores data in data blocks. A redundancy is established, the redundancy being a number of data blocks for a parity block. A plurality of parity sets is established, a parity set having the number of data blocks for a parity block and having a set parity block. The set parity block for each parity set is computed. Each set parity block is stored on one of the data storage devices that does not store one of the data-block members of the parity set, to store more than one parity block on each storage device, with an exception that two parity blocks for the same data storage location are precluded from being stored on the same data storage device.