Various embodiments of the present invention are generally directed to an apparatus and method for providing a fault-tolerant non-volatile buddy memory structure, such as a buddy cache structure for a controller in a data storage device. A semiconductor memory array of blocks of non-volatile resistive sense memory (RSM) cells is arranged to form a buddy memory structure comprising a first set of blocks in a first location of the array and a second set of blocks in a second location of the array configured to redundantly mirror the first set of blocks. A read circuit decodes a fault map which identifies a defect in a selected one of the first and second sets of blocks and concurrently outputs data stored in the remaining one of the first and second sets of blocks responsive to a data read operation upon said buddy memory structure.