L2P Table Relocation in CXL Memory Compression After DRAM Corruption
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Solution Overview
Problem
Existing memory systems face challenges in preserving the integrity of critical logical-to-physical (L2P) addressing tables stored on dynamic random access memory (DRAM), as they are susceptible to degradation and corruption, leading to system failure when error correction methods become ineffective.
Innovation Solution
Implementing a system that triggers the movement of the L2P table to a new, error-free location within the DRAM when corruption is detected, using error detection and correction mechanisms like Chipkill and Reed-Solomon codes, and maintaining an uncorrupted version of the L2P table by copying it to new dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction methods (Chipkill, Reed-Solomon) are used to preserve L2P table integrity, then reliability is improved, but device complexity increases due to additional correction mechanisms
Solution Approach 1:
The system performs preliminary error detection and correction actions before the L2P table corruption becomes critical. Error correction codes are proactively applied to detect and fix errors in L2P table entries before they cause system failure, maintaining reliability while managing complexity through preventive rather than reactive measures
Solution Approach 2:
The patent implements copying of the L2P table to alternative memory locations when corruption is detected. Instead of relying solely on complex error correction mechanisms, the system creates redundant copies of the L2P table in different memory regions, allowing recovery without requiring the original corrupted data, thus reducing dependence on complex correction algorithms
2Speed
If L2P table is stored in DRAM to enable fast access, then speed is improved, but reliability deteriorates due to DRAM degradation and corruption over time
Solution Approach 1:
The L2P table is copied to multiple DRAM locations and potentially to more persistent storage media. This redundancy allows the system to maintain fast access speeds by serving from DRAM while having backup copies available if degradation or corruption occurs, thus resolving the contradiction between speed and reliability
Solution Approach 2:
The system performs preliminary integrity checks on L2P table data in DRAM and proactively triggers table regeneration or switching to backup copies before corruption becomes critical. This preventive approach maintains both fast access speeds and reliability by addressing degradation issues before they cause failures
3Reliability
If L2P table movement is triggered immediately upon corruption detection, then reliability is improved, but productivity decreases due to additional clock cycles and energy consumption
Solution Approach 1:
Instead of immediately moving the entire L2P table upon any corruption detection, the system applies partial correction to affected entries using error correction codes. Only when corruption exceeds correction capability does the system trigger a full table movement, thus maintaining productivity while ensuring reliability through graduated response
Solution Approach 2:
The system prepares backup L2P table copies in advance and performs incremental updates rather than full movements. When corruption is detected, pre-prepared backup copies can be quickly activated with minimal performance impact, reducing the productivity penalty while maintaining high reliability
Data Source
AI summary
Provided in a central controller system, is a system and method to identify and mitigate errors on a die containing mission critical logical-to-physical addressing information. The logical-to-physical (L2P) addressing information is essential for translating logical memory addresses for uncompressed data to physical addresses for compressed data. When a die containing L2P data is detected as being corrupted, the corrupted data is corrected, and all the data is moved to an uncorrupted die at a specified offset from the original address of the die.