US Patent 8463991 Intra-device data protection in a raid array

A system and method for intra-device data protection in a RAID array. A computer system comprises client computers and data storage arrays coupled to one another via a network. A data storage array utilizes solid-state drives and Flash memory cells for data storage. A storage controller within a data storage array is configured to identify a unit of data stored in the data storage subsystem, wherein said unit of data is stored across at least a first storage device and a second storage device of the plurality of storage devices, each of the first storage device and the second storage device storing intra-device redundancy data corresponding to the unit of data; and change an amount of intra-device redundancy data corresponding to the unit of data on only the first storage device.