A storage subsystem receives writes from a computer via a standard storage subsystem interface. The storage subsystem reduces a number of the writes. A single drive of the storage subsystem has primary and redundant storage devices with storage device interfaces. A disk controller of the single drive implements a data redundancy scheme by storing data associated with the reduced number of writes in the primary storage devices and by storing computed redundancy information in the redundant storage devices. The disk controller is operable without a loss of data in the presence of at least a single failure of any of the storage devices. Optionally the storage devices are flash memory devices. Optionally the disk controller is operable without a loss of data in the presence of at least two failures of any of the storage devices when a number of the redundant storage devices is at least two.