Method and apparatus for mapping data in a heterogeneous disk array storage system

Computer systems are constantly improving in terms of processing speed and reliability. As these systems improve, demands for improvements in mass storage systems in terms of I/O performance, availability and storage capacity also increase. In order to address these demands, RAID storage systems have been developed. RAID is an acronym that originally stood for "Redundant Arrays of Inexpensive Disks". Today, the "I" in RAID commonly stands for "independent". A RAID data storage system includes a heterogenous disk array coupled to a controller. The disk array provides a storage space that includes a first set of stipes each having at least "N" blocks and a second set of stripes each having less than "N" blocks. The controller can operate to map the storage space into redundant units by creating at least one redundant unit for storing data according to a mirror redundancy scheme. The redundant unit includes a block from the first set of stripes and a block from the second set of stripes.