Flash Memory Controller Write Sequence Number Mapping Reconstruction
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Solution Overview
Problem
Flash memory devices, such as NAND Flash, face challenges in maintaining data integrity and rebuilding mapping tables after a power-off state due to the loss of the mapping table stored in random access memory, leading to issues with data recovery and page validation.
Innovation Solution
A data storage device with a controller that assigns write sequence numbers to write commands and stores them in flash memory blocks, allowing for the reconstruction of a physical-logical mapping table upon power restoration by identifying and invalidating damaged pages based on sequence numbers and logical addresses, ensuring accurate data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mapping table is stored in random access memory for efficient data access, then data access speed is improved, but the mapping table is lost when power turns off unexpectedly
Solution Approach 1:
The patent applies preliminary action by storing the mapping table in both random access memory for fast access and in flash memory as a backup before power loss occurs. This dual-storage approach ensures that when power turns off unexpectedly, the mapping table information is preserved in flash memory and can be used to reconstruct the RAM mapping table during power restoration, thus preventing data loss while maintaining fast access speeds during normal operation
2Reliability
If the controller rebuilds the mapping table by reading all blocks after power restoration, then data integrity is ensured, but the time required for resumption increases
Solution Approach 1:
The patent applies the taking out principle by extracting and utilizing the backup mapping table information that was previously stored in flash memory during normal operation. When power is restored, instead of reading all blocks to rebuild the mapping table, the controller extracts the preserved mapping table information from flash memory, significantly reducing resumption time while ensuring data integrity through the use of this pre-saved reliable information
3Measurement precision
If write sequence numbers are assigned and stored with each data sector, then data recovery accuracy is improved, but the storage space requirement increases
Solution Approach 1:
The patent applies partial action by implementing write sequence numbers only in the spare area of flash memory pages rather than duplicating them throughout the entire data structure. This selective placement provides sufficient information for accurate data recovery and mapping table reconstruction while minimizing the additional storage space consumed, as the sequence numbers are stored only where necessary for the recovery process
Data Source
AI summary
The present invention provides a data storage device including a flash memory and a controller. The flash memory includes a plurality of blocks, wherein each of the blocks has a plurality of pages. The controller receives a plurality of write commands in a sequence, assigns a plurality of write sequence numbers to the write commands according to the sequence in which the write commands are received, and writes a plurality of data sectors and the write sequence numbers of the write commands into the pages of a first current block and a second current block of the blocks according to the write commands.