Dynamic Recording Density Control in Mass Storage
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Solution Overview
Problem
Current disk drives face challenges in improving reliability and performance due to fixed sector sizes and rigid arithmetic relationships between logical and physical block sizes, limiting flexibility and features in data storage.
Innovation Solution
A dynamically mapped storage device that adjusts recording density based on physical capacity utilization, allowing data to be written at lower densities when space is unused and migrating data to nominal densities as capacity increases, while monitoring and managing recording density through a utilization monitor and density controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is written at higher recording density to increase storage capacity, then capacity utilization improves, but reliability deteriorates due to increased error probabilities
Solution Approach 1:
The patent implements dynamic adjustment of recording density based on capacity utilization thresholds. When utilization is below a first threshold, data is written at higher density to maximize capacity. When utilization exceeds the first threshold but remains below a second threshold, the system transitions to nominal density. When utilization exceeds the second threshold, data is written at lower density to prioritize reliability. This dynamic approach resolves the contradiction by adapting recording density to current storage conditions rather than using a fixed density mode.
Solution Approach 2:
The system changes the recording density parameter based on capacity utilization monitoring. By monitoring the ratio of used capacity to total capacity and comparing it against predefined thresholds, the system adjusts the recording density parameter to optimize the balance between storage capacity and data reliability. This parameter change strategy allows the system to achieve high capacity utilization while maintaining acceptable reliability levels through conditional density adjustment.
2Ease of manufacture
If fixed sector sizes and rigid arithmetic relationships are used between logical and physical block sizes, then manufacturing and operation become simpler, but adaptability and versatility deteriorate
Solution Approach 1:
The patent introduces dynamic mapping between logical block addresses (LBA) and physical block addresses (PBA) that can adapt to different recording density modes. The mapping structure is not fixed but can be reconfigured based on the current recording density, allowing the system to maintain simple arithmetic relationships when needed while providing adaptability when density changes. This dynamic mapping resolves the contradiction by making the relationship between logical and physical blocks flexible rather than rigid.
Solution Approach 2:
The storage space is segmented into different density zones or regions that can be independently managed. The system can divide the addressable space into segments with different recording density characteristics, allowing some portions to use fixed simple mappings while others use adaptive mappings. This segmentation enables the coexistence of manufacturing simplicity and operational adaptability by applying different mapping strategies to different portions of the storage medium.
Data Source
AI summary
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.