SSD Logical-to-Physical Address Mapping Partitioning
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Solution Overview
Problem
Large capacity solid state drives (SSDs) face challenges in managing logical to physical address mapping due to the size constraints of random access memory (RAM) in SSD controllers, as the flash translation layer (FTL) requires a large Logical-to-Physical (L2P) table that exceeds the available RAM capacity, leading to performance and endurance issues with existing solutions.
Innovation Solution
The SSD is divided into a front-end and back-end operational parts, with the entire L2P table stored in non-volatile memory (NVM) and split into partitions, where a partition table in RAM allows for on-demand access and management of these partitions, eliminating the need for increased RAM capacity and minimizing RAM usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the L2P table is stored entirely in RAM memory in the SSD controller, then fast random access to mapping information is achieved, but the RAM capacity requirement becomes prohibitively large for high-capacity SSDs
Solution Approach 1:
The L2P table is divided into multiple partitions stored in non-volatile memory, with a partition table stored in RAM containing pointers to these partitions. This segmentation allows the system to access only the necessary partition rather than loading the entire L2P table into RAM, thereby reducing RAM capacity requirements while maintaining access speed to the needed mapping information.
2Quantity of substance
If the L2P table is stored in non-volatile memory instead of RAM, then RAM capacity requirements are reduced, but access speed to the L2P table decreases
Solution Approach 1:
The partition table is pre-loaded into RAM, containing all the pointer information needed to locate L2P partitions in non-volatile memory. This preliminary action in RAM allows for fast lookup of the required partition address, enabling the system to quickly access specific L2P partitions in non-volatile memory without scanning the entire table, thus maintaining access speed while reducing RAM capacity requirements.
3Productivity
If the SSD controller uses larger RAM memory to accommodate the L2P table, then mapping management performance is improved, but power consumption and device cost increase
Solution Approach 1:
By segmenting the L2P table into partitions stored in non-volatile memory and keeping only the partition table in RAM, the system maintains mapping management performance through efficient partition lookup while dramatically reducing the RAM capacity required. This reduction in RAM capacity directly lowers power consumption and device cost without significantly compromising mapping management performance.
Data Source
AI summary
Aspects of the disclosure provide for managing a logical to physical (L2P) table in a Solid State Drive (SSD). Methods and apparatus provide for using a non-volatile memory (NVM) to store the L2P table in its entirety, where the L2P table is separated into a plurality of partitions. The SSD is partitioned into front and back-end processing portions where a partition table is managed by the back-end portion and includes one or more addresses of partitioned portions of the plurality partitions of the L2P table stored in the NVM. The back-end processing portion receives requests from the host via the front-end processing portion and accesses the partition table for scheduling read or write access to the NVM by determining one or more addresses of the respective partitioned portions of the plurality partitions of the L2P table stored in the NVM from the partition table.