Methods and structures for performing field flawscan to reduce manufacturing costs of a dynamic mapped storage device. In a dynamic mapped storage device in which all user supplied logical blocks are dynamically mapped by the storage device controller to physical disk blocks, features and aspects hereof permit flawscan testing of a storage device to be completed substantially concurrently with processing write requests for its intended application. A fraction of the storage device may be certified by an initial flawscan performed during manufacturing testing. Statistical sampling sufficient to assure a high probability of achieving specified capacity may be performed to reduce manufacturing time and costs in testing. Final flawscan of the remainder of the storage locations may be performed substantially concurrently with processing of write requests after the device is installed for its intended application. Mapping features and aspects hereof allow the storage device controller to perform flawscan and write operations concurrently.