Abstract: Methods and structures for dynamic density control to improve reliability of a dynamically mapped storage device. In a dynamically 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 provide for dynamically altering the recording density of user data stored on the storage device. So long as the physical capacity utilization of the storage device permits, new data stored on the device may be stored at lower density to improve reliability in reading back the recorded data. Further features and aspects hereof may reduce the recording density only for data deemed to be critical. Radial (track) density, longitudinal (bit) density, or both may be dynamically controlled to reduce recording density. As physical capacity utilization increases, data previously recorded at lower density may be migrated (re-recorded) at normal higher density.

Abstract: Methods and structures for dynamic multiple indirections to improve reliability and performance of a dynamically mapped storage devices. In a dynamically 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 provide for dynamically altering the number of replicated copies (multiple mapped indirections) of user data stored on the storage device. Performance information regarding operation of the storage device may be gathered by the storage device controller such that where physical capacity of the storage device permits and as degrading reliability is detected, additional copies (multiple indirections) of stored user data may be written to the mapped storage device. Increased multiple indirections improves reliability by decreasing the probability of data loss in response to various failure modes of the storage device.