L2P Table Management Using Low-Latency NVM
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Solution Overview
Problem
The increasing demand for large capacity flash storage devices poses challenges in managing metadata, as the required RAM size grows exponentially, leading to high fabrication costs and power consumption, making it impractical to store the logical to physical (L2P) table in RAM for devices with capacities above 64 TB.
Innovation Solution
Implementing low-latency non-volatile memory (NVM) to store L2P table snapshots and journal records, reducing the RAM requirements to 3-6% of the original, allowing for efficient metadata management and avoiding write collisions between journal and user data writes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If RAM size is increased to accommodate metadata for large capacity flash storage devices, then metadata access performance is improved, but fabrication costs and power consumption increase
Solution Approach 1:
The patent segments the metadata storage system into multiple components: a small high-speed cache in RAM for frequently accessed metadata, and a larger capacity storage in low-latency NVM for the complete L2P table. This segmentation allows the system to maintain fast access performance for critical operations while avoiding the need to allocate large amounts of power-consuming RAM for the entire metadata structure.
2Speed
If RAM size is increased to accommodate metadata for large capacity flash storage devices, then metadata access performance is improved, but fabrication costs increase
Solution Approach 1:
The patent segments the metadata storage system into multiple components: a small high-speed cache in RAM for frequently accessed metadata, and a larger capacity storage in low-latency NVM for the complete L2P table. This segmentation allows the system to maintain fast access performance for critical operations while avoiding the need to allocate large amounts of power-consuming RAM for the entire metadata structure.
3Quantity of substance
If low-latency NVM is used to store L2P table snapshots and journal records, then RAM requirements are reduced, but write operation complexity increases
Solution Approach 1:
The patent implements preliminary action by maintaining journal records and L2P table snapshots in low-latency NVM before actual write operations occur. This allows the system to prepare metadata updates in advance and quickly apply them during write operations, reducing the complexity of real-time metadata management while maintaining reduced RAM requirements.
4Loss of time
If low-latency NVM is used to store L2P table snapshots and journal records, then system downtime during L2P table rebuilds is minimized, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by maintaining journal records and L2P table snapshots in low-latency NVM before actual write operations occur. This allows the system to prepare metadata updates in advance and quickly apply them during write operations, reducing the complexity of real-time metadata management while maintaining reduced RAM requirements.
Data Source
AI summary
Disclosed are systems and methods for providing logical to physical (L2P) table management using low-latency NVM to reduce solid state drive (SSD) random access memory (RAM) footprint. A method includes determining a logical to physical (L2P) mapping of a logical address to a physical address in a flash storage, for an operation directed to the logical address. The method also includes adding a data entry, comprising the L2P mapping, to an open journal structure in RAM. The method also includes adding a log entry, comprising the L2P mapping, to a buffer in the RAM. The method also includes flushing the buffer to a low-latency NVM storage in response to determining that the buffer has satisfied a size threshold. Reads, snapshotting and L2P table recovery are also described.