Flash Memory Controller Page Duplication for Address Mapping Recovery
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Solution Overview
Problem
Flash memory storage devices face challenges in managing physical-to-logical address mapping information, particularly during power recovery processes, as temporary data in random access memory can be lost due to unexpected power-offs, leading to unreliable address mapping.
Innovation Solution
A data storage device with a control unit that duplicates the last write page of a run-time write block during power recovery to generate a duplicated page, using this information to rebuild the physical-to-logical address mapping table instead of relying on potentially damaged data from the last write page, ensuring reliable address mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mapping information is temporarily stored in random access memory for easy management, then ease of operation is improved, but reliability deteriorates due to unexpected power-off events causing data loss
Solution Approach 1:
The patent applies preliminary action by duplicating the last write page data before power-off can occur. During normal operation, the controller maintains mapping information in RAM for easy access, and simultaneously creates a duplicate copy in a reserved area of the flash memory. This advance duplication ensures that if power is lost, the copied data survives and can be used to restore the mapping table.
Solution Approach 2:
The patent applies copying by creating a duplicate copy of the critical mapping information (last write page) in a different storage location. The original mapping information remains in RAM for operational efficiency, while a copy is stored in the flash memory's reserved area. This copying strategy allows the system to retrieve the duplicate during power recovery to rebuild the mapping table.
2Device complexity
If mapping information is restored from the last write page during power recovery, then device complexity is reduced, but reliability deteriorates due to potential data damage from unexpected power-off
Solution Approach 1:
The system performs preliminary duplication of the last write page during normal operation, so that during power recovery, the controller can directly use the pre-copied data without complex data recovery operations. This advance preparation simplifies the recovery process while ensuring data integrity.
Solution Approach 2:
The patent introduces a reserved area in the flash memory as an intermediary storage location. This intermediary holds a duplicate copy of the mapping information, serving as a bridge between the volatile RAM and the permanent flash storage. During power recovery, this intermediary provides reliable data without requiring complex restoration operations.
3Reliability
If duplicate pages are created in run-time write blocks during power recovery, then reliability is improved through redundancy, but device complexity increases due to additional management operations
Solution Approach 1:
The patent applies local quality by creating a duplicate page only in a specific location (the next page of the run-time write block) rather than duplicating throughout the entire storage structure. This localized duplication provides the necessary redundancy while minimizing the complexity of tracking and managing multiple copies across the entire flash memory.
Solution Approach 2:
The system discards the potentially damaged last write page data and recovers by using the duplicate page instead. During power recovery, the controller identifies that the original last write page may be corrupted, discards it, and recovers the mapping information from the safely stored duplicate page in the reserved area.
Data Source
AI summary
A flash memory control technology with high reliability. In a power recovery process, a microcontroller is configured to duplicate a last write page of a run-time write block of a flash memory and thereby generate a duplicated page in the run-time write block to replace the last write page for reliability enhancement.