Nonvolatile Memory Controller Mapping Table Recovery
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Solution Overview
Problem
Storage devices with nonvolatile memory face delays in operations due to the need to recover a mapping table after unexpected power-offs, which can erase the mapping table from volatile memory, thereby disrupting write, read, and erase operations.
Innovation Solution
A storage device and method that generates and uses check data to quickly recover the mapping table by predicting logical and physical addresses based on the continuity and offset between addresses, reducing the time required for map recovery by skipping unnecessary pages during the recovery process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mapping table is stored in volatile memory for fast access, then operation speed is improved, but data reliability deteriorates due to sudden power-off erasing the mapping table
Solution Approach 1:
The patent applies preliminary action by generating and storing check data (including offset values and sequence information) in advance during normal write operations. This check data is stored in the nonvolatile memory alongside the actual data, so when sudden power-off occurs and the mapping table is lost from volatile memory, the system can immediately use this pre-stored check data to recover the mapping table without needing to perform time-consuming full scans, thus maintaining both fast operation and reliability.
2Reliability
If the mapping table is recovered by scanning all pages after sudden power-off, then complete recovery is achieved, but time consumption increases significantly
Solution Approach 1:
The patent extracts only the essential recovery information (offset values and sequence numbers) from the check data stored at each page, rather than scanning and analyzing all page contents. By taking out just these critical elements that indicate page sequences and offsets, the system can rapidly reconstruct the mapping table structure without the time-consuming process of examining every page, thus achieving complete recovery with minimal time loss.
Solution Approach 2:
The patent applies partial action by using only the necessary portion of stored check data (offset values and sequence information from the last page) for mapping table recovery, rather than processing all stored data. This selective use of minimal necessary information enables fast recovery while ensuring completeness, as the offset and sequence data contain all essential structural information needed to reconstruct the mapping table.
3Measurement precision
If check data is generated and stored for every page, then mapping recovery accuracy is improved, but memory space consumption increases
Solution Approach 1:
The patent applies local quality by storing different types of information at different locations: the actual data is stored in the main data area of each page, while compact check data (offset values and sequence numbers) is stored locally in the spare area of each page. This localized storage of minimal recovery-critical information at each page provides high recovery accuracy without requiring additional memory space, as the check data utilizes otherwise unused spare areas.
Data Source
AI summary
A storage device includes a nonvolatile memory device and a memory controller. After writing first data at the first page, the memory controller writes second data at a second page. The memory controller generates first check data corresponding to the first data and second check data corresponding to the second data. The memory controller recovers the first and second physical addresses and the first and second logical addresses based on the second check data.