SSD Controller Signaling for Adaptive Error Correction and NAND Management
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Solution Overview
Problem
Current solid-state drive (SSD) systems face inefficiencies in error correction, garbage collection, data write operations, power distribution, and wear leveling, which affect performance and longevity, particularly due to inadequate control over NAND memory types and block management.
Innovation Solution
The implementation of an extended command and status signal system between the host device and SSD controller allows for dynamic control over error correction, garbage collection, data write operations, power distribution, and NAND memory management, enabling adaptive optimization of SSD performance and longevity by switching between different decoders, managing block allocation, and redistributing power based on performance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction methods are used in SSD systems, then error correction functionality is provided, but read time increases and processing efficiency decreases
Solution Approach 1:
The patent applies partial action by implementing a two-stage error correction approach: first using a fast LDPC decoder to correct easily correctable errors, and only switching to the slower BCH decoder when the LDPC decoder fails to correct all errors. This partial application of the more powerful but slower correction method significantly reduces average read time while maintaining high error correction capability.
Solution Approach 2:
The error correction function is segmented into two independent decoder components: an LDPC decoder for fast correction of common errors and a BCH decoder for handling more difficult error cases. By dividing the error correction task into segments with different complexity levels, the system achieves both speed and reliability.
2Reliability
If standard garbage collection procedures are used, then memory management is maintained, but data write efficiency decreases and performance is reduced
Solution Approach 1:
The patent implements preliminary action by performing proactive garbage collection operations before the SSD runs out of available blocks. The controller monitors block usage and initiates garbage collection in advance, consolidating valid data and freeing blocks before they are critically needed, thereby avoiding write amplification and maintaining high write efficiency.
Solution Approach 2:
The system uses feedback mechanisms to monitor SSD internal state including block availability, wear levels, and performance metrics. Based on this feedback, the controller dynamically adjusts garbage collection timing and intensity, optimizing the balance between memory management and write performance.
3Ease of operation
If uniform power distribution is applied to all NAND memory blocks, then power management is simplified, but performance optimization and longevity are reduced
Solution Approach 1:
The patent applies local quality by distributing power non-uniformly across different NAND memory blocks based on their specific needs. The controller monitors individual block characteristics such as wear level, temperature, and performance degradation, then allocates power dynamically to specific blocks or groups of blocks that require it, optimizing both performance and longevity.
Solution Approach 2:
Power distribution is made dynamic rather than static. The system continuously adjusts power allocation to NAND blocks based on real-time conditions including workload demands, block wear states, and thermal conditions, allowing the SSD to adapt power resources optimally to current operational requirements.
4Duration of action of stationary object
If aggressive wear leveling is implemented, then block lifespan is extended, but write performance and speed are reduced
Solution Approach 1:
The patent applies partial action in wear leveling by selectively applying wear-leveling operations only to blocks that are approaching their end-of-life threshold, rather than uniformly redistributing data across all blocks. This selective approach extends the lifespan of critical blocks without the performance penalty of aggressive global wear leveling.
Solution Approach 2:
The system changes the wear-leveling parameter from aggressive uniform redistribution to selective threshold-based redistribution. By monitoring block program/erase cycle counts and initiating wear leveling only when blocks approach their endurance limits, the system maintains write performance while still extending overall SSD lifespan.
Data Source
AI summary
According to one embodiment, a memory system includes a nonvolatile memory and a controller which controls the nonvolatile memory. The controller notifies to an outside an extensive signal which indicates a predetermined state of the nonvolatile memory or the controller.