Memory Controller Patrol Scrubbing for Adaptive ECC Reliability
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Solution Overview
Problem
Volatile memory devices face performance degradation due to increased scaling, leading to higher defect probabilities, while non-volatile memory devices require improved reliability and error correction mechanisms.
Innovation Solution
A memory system with a memory controller that performs adaptive patrol scrubbing operations, adjusting scrubbing cycles based on error count values and risk thresholds, and incorporates an Error Correction Code (ECC) engine for error detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory devices are scaled down to increase memory capacity in smaller chip, then memory capacity and integration are improved, but defect probability and performance degradation increase
Solution Approach 1:
The patent implements patrol scrubbing operations that proactively read and correct errors in memory devices before they become unrecoverable failures. The controller performs periodic scrubbing of ECC-correctable errors, preventing their progression to uncorrectable error states, thus maintaining reliability as memory devices are scaled down.
Solution Approach 2:
The system monitors error counts from ECC operations and uses this feedback to dynamically adjust scrubbing cycles. When error counts increase, indicating deteriorating memory reliability, the controller shortens the scrubbing cycle to more frequently detect and correct errors, preventing catastrophic failures in scaled-down memory devices.
2Ease of operation
If fixed scrubbing cycles are used for all memory devices, then control simplicity is maintained, but reliability optimization for devices with different error characteristics is reduced
Solution Approach 1:
The patent transitions from static fixed scrubbing cycles to dynamic adaptive scrubbing cycles. The controller adjusts scrubbing intervals based on real-time error count feedback from ECC operations. Memory devices exhibiting higher error rates receive more frequent scrubbing, while stable devices maintain longer intervals, optimizing reliability without excessive complexity.
3Reliability
If patrol scrubbing operations are performed frequently to detect and correct errors, then reliability is improved, but power consumption and operational overhead increase
Solution Approach 1:
The system dynamically changes the scrubbing cycle parameter based on error characteristics. Instead of using a constant frequent scrubbing interval, the controller adjusts the time between scrubbing operations according to the memory device's error rate. This reduces power consumption for devices with low error rates while maintaining high reliability for devices showing signs of degradation.
Data Source
AI summary
A memory system, a memory controller are provided. The memory system includes: a memory device; and a memory controller configured to: control a patrol scrubbing operation in which data is read from and re-written to the memory device, based on a scrubbing cycle; and adaptively adjust the scrubbing cycle based on a comparison of an error count value of the memory device and a plurality of risk threshold values.