A computer program product includes a computer readable storage medium having program instructions embodied therewith, wherein the program instructions are executable by a processor to cause the processor to perform a method. The method includes storing an operating system in minor stripes on a first data storage device forming a first logical storage unit, and storing data in major stripes across a plurality of data storage devices forming a second logical data storage unit. Each major stripe includes a plurality of minor stripes storing data and a parity stripe. The method further includes calculating the parity stripe from the plurality of minor stripes within the major stripe and a corresponding one of the minor stripes on the first data storage device, wherein the minor stripes on the first data storage device match the size of the minor stripes on the array of data storage devices.