SSD Mapping Information Embedding for Fast Recovery
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Solution Overview
Problem
Current solid state drives (SSDs) face inefficiencies in rebuilding mapping information between logical and physical addresses after a power loss, requiring a time-consuming scan of all valid pages, which affects performance and power consumption.
Innovation Solution
Embedding mapping information within the last valid page of each logical block, allowing for efficient retrieval by scanning only that page instead of the entire device, thereby reducing the need for extensive scanning and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mapping information is stored in volatile memory and periodically updated to non-volatile memory, then mapping information can be retrieved during start-up, but if power is lost abruptly, extensive scanning of all valid pages is required to rebuild mapping information, causing significant time loss and reduced productivity
Solution Approach 1:
The patent embeds mapping information directly within the last valid page of each logical block in non-volatile memory before power loss can occur. This preliminary placement of mapping information ensures that upon recovery, the system can immediately access the most recent mapping data without needing to scan all valid pages, thus resolving the time loss issue while maintaining reliability
Solution Approach 2:
The patent extracts mapping information from volatile memory and permanently stores it within the non-volatile memory structure (specifically in the last valid page of each logical block). This extraction ensures that mapping information survives power loss and eliminates the need for time-consuming reconstruction, addressing both reliability and time loss concerns
2Reliability
If mapping information is updated to non-volatile storage with each write operation, then mapping information is always current, but this significantly increases power consumption and reduces device efficiency
Solution Approach 1:
The patent merges mapping information storage with the existing valid page structure in non-volatile memory. By embedding mapping information within the last valid page of each logical block, the system maintains current mapping information without requiring separate update operations, thus avoiding excessive power consumption while ensuring accuracy
Solution Approach 2:
The mapping information is automatically updated as part of the normal write operation process without requiring additional power-intensive operations. The system uses the existing write path to simultaneously update both data and mapping information, eliminating redundant power consumption while maintaining accuracy
3Reliability
If extensive scanning of all valid pages is performed to rebuild mapping information after power loss, then complete mapping information can be recovered, but this causes the SSD to be unavailable for an extended period, reducing productivity and performance
Solution Approach 1:
Mapping information is pre-positioned within the last valid page of each logical block in non-volatile memory before any power loss event. This preliminary arrangement allows immediate recovery without scanning, maintaining both completeness and availability
Solution Approach 2:
The patent extracts mapping information from the volatile memory system and permanently embeds it in non-volatile memory structure. This extraction eliminates the need for time-consuming scanning operations while ensuring complete mapping information is available immediately upon power restoration, thus maintaining productivity
Data Source
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AI summary
Memory modules and methods of operating memory modules embed mapping information within blocks of memory cells to which the mapping information pertains. In particular, when a page is written for a logical data block, that page includes a snapshot of the current mapping information for that logical data block. In this manner, the last valid physical page of a logical data block will contain a physical/logical mapping of that block. Thus, instead of scanning every valid page of the memory device to rebuild the mapping information, the memory module may scan only for the last valid physical page of each logical data block. Once the last valid physical page is discovered for a logical data block, the latest mapping information for that logical data block may be read from that page.