Memory Controller Read Reclaim Count Adjustment
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Solution Overview
Problem
Memory systems face challenges in performing read reclaim operations effectively, especially after a sudden power-off (SPO), where data integrity and reliability are compromised due to failed bits exceeding thresholds, leading to inefficient data recovery.
Innovation Solution
A memory system and method that selectively manage memory blocks by adjusting the read reclaim count value based on the occurrence of SPO, using a controller to identify and prioritize memory blocks with high failure rates, and employing schemes like round robin or linked lists to prevent repeated selection, thereby optimizing data recovery during booting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read reclaim operations are performed after sudden power-off, then data recovery capability is improved, but system complexity increases due to need for block selection and count management
Solution Approach 1:
The controller pre-manages memory blocks by maintaining a list of candidate blocks that may need read reclaim operations. When sudden power-off occurs, the system only needs to execute read reclaim on pre-identified candidate blocks rather than scanning all blocks, thus improving data recovery capability while limiting the complexity increase to only managing the candidate block list.
2Reliability
If read reclaim count value is increased for memory blocks with high failure rates, then data integrity is improved, but operation time increases due to additional read operations
Solution Approach 1:
The controller applies different read reclaim count values to different memory blocks based on their individual failure rates. Memory blocks with high failure rates receive higher read reclaim counts for enhanced data integrity, while blocks with low failure rates receive standard counts. This localized differentiation improves overall data integrity without uniformly increasing operation time across all blocks.
Solution Approach 2:
The system dynamically adjusts the read reclaim count parameter based on the failure rate characteristics of each memory block. By changing this parameter selectively rather than using a fixed value for all blocks, the system optimizes the balance between data integrity and operation time, applying additional read operations only where necessary.
3Productivity
If memory blocks are selected based on SPO occurrence number, then read reclaim efficiency is improved, but measurement precision requirements increase for tracking SPO events
Solution Approach 1:
The controller automatically tracks sudden power-off events and maintains an SPO occurrence number for each memory block without requiring external intervention or complex measurement systems. This self-service approach improves read reclaim efficiency by using the tracked SPO information to prioritize candidate blocks, while keeping measurement precision requirements manageable through simple counter-based tracking.
Data Source
AI summary
A memory system includes: a memory device including a plurality of memory blocks; and a controller suitable for selecting one or more first memory blocks based on a predetermined condition among the plurality of the memory blocks in a booting section, and increasing a read reclaim count value of one or more second memory blocks among the one or more first memory blocks for which a number of failed bits of read data exceeds a predetermined threshold.