SSD Controller S-Journal Segmentation for Startup and Write Reduction
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Solution Overview
Problem
Conventional SSDs face inefficiencies in data management due to the large size of the Logical to Physical (L2P) map table, which requires frequent updates and storage in volatile memory, leading to slow startup times and high Write Amplification (WA) during random writing operations.
Innovation Solution
A hardware-based garbage collection scheme is implemented using S-Journals and S-Blocks, which reduces the need to update the entire L2P map table by creating journal entries for each write operation, allowing for efficient reconstruction of the map upon power loss and minimizing unnecessary writes to non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large L2P map table is used to map logical entries to physical address locations, then address translation capability is improved, but startup time increases and memory requirements increase
Solution Approach 1:
The patent divides the large L2P map table into multiple smaller segments that can be loaded independently into DRAM. Only the necessary segments are loaded during startup, significantly reducing startup time while maintaining full address translation capability. The segments are organized to allow selective loading based on actual usage patterns.
Solution Approach 2:
The patent performs preliminary organization of the L2P map data into segments during manufacturing or initial setup, preparing the data structure in advance. This allows the system to quickly load only required segments during startup rather than loading the entire map table, achieving fast initialization while preserving complete mapping functionality.
2Reliability
If the entire L2P map table is saved to non-volatile memory during writes, then data consistency is improved, but write amplification increases
Solution Approach 1:
The patent extracts only the modified portions of the L2P map table (specific segments containing updated entries) and saves them to non-volatile memory, rather than saving the entire map table. This extraction approach maintains data consistency for updated entries while dramatically reducing write amplification by avoiding redundant writes of unchanged data.
Solution Approach 2:
The patent applies partial action by saving only the necessary portion of the L2P map table (the modified segments) to non-volatile memory. This partial update strategy ensures data consistency where needed while avoiding the excessive write operations that would result from saving the complete map table on every write operation.
3Adaptability or versatility
If random writing operations are performed, then data access flexibility is improved, but the number of required map table updates increases
Solution Approach 1:
The patent segments the L2P map table to allow independent updates of specific segments corresponding to randomly written data. When random writes occur, only the affected map segments need to be updated and saved, rather than requiring updates to the entire map table. This segmentation maintains data access flexibility while improving write efficiency by limiting the scope of required updates.
Data Source
AI summary
A solid state drive controller includes a processor configured to couple to a plurality of non-volatile memory devices. The plurality of non-volatile memory devices are configured to store a plurality of system journals and a plurality of physical pages. The solid state drive controller also includes a volatile memory configured to store a logical-to-physical address translation map configured to enable the solid state drive controller to determine a physical location of at least one logical page. The processor is configured to maintain the plurality of system journals in the plurality of non-volatile memory devices, wherein each system journal defines physical-to-logical page correspondences for a predetermined range of the plurality of physical pages, and each system journal comprises an identification number that includes a portion of an address of a first physical page of the predetermined range of the plurality of physical pages.