Multi-Level Cell Maintenance With Buffered Error Control
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Solution Overview
Problem
Existing memory systems face reliability and latency issues during two-portion maintenance operations due to multiple read operations and extended durations between passes, which can lead to uncorrectable errors and increased latency in multi-level cell maintenance.
Innovation Solution
Implementing a memory system controller that stores data from a first error control operation in a portion of the memory system, such as SLC blocks or volatile memory, and uses this data during the second portion of the maintenance operation to reduce latency and increase reliability by skipping redundant error control operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple read operations are performed during two-portion maintenance operations, then data can be verified and corrected, but latency increases and reliability decreases due to extended duration between passes
Solution Approach 1:
The patent performs the first error control operation and stores its results in a buffer memory before the second pass. This preliminary action allows the second pass to reuse the stored error control data, eliminating the need to re-read and re-process the same data, thereby reducing latency while maintaining reliability through redundant verification.
Solution Approach 2:
The patent introduces a buffer memory as an intermediary component that stores error control operation results between the first and second passes. This intermediary allows efficient data retrieval and reuse, reducing the time penalty associated with multiple read operations while ensuring data integrity through repeated verification.
2Reliability
If error control operations are performed multiple times during maintenance, then data reliability improves, but processing latency increases
Solution Approach 1:
The patent creates a copy of the error control operation results from the first pass and stores it in buffer memory for use during the second pass. This copying approach allows the system to perform redundant error control operations for reliability while avoiding the latency of re-processing, as the copied results can be directly reused.
Solution Approach 2:
The error control operation is performed in advance during the first pass, and its results are preserved in buffer memory. This preliminary execution of the error control function allows the second pass to benefit from pre-computed error correction data, maintaining high reliability through redundant checking while improving productivity by eliminating duplicate processing.
3Ease of operation
If extended duration is allowed between maintenance operation passes, then more thorough error control can be performed, but data reliability decreases due to increased risk of uncorrectable errors
Solution Approach 1:
The patent maintains continuity of the error control function by buffering results between passes and immediately reusing them in the second pass. This continuous approach ensures thorough error control is performed without allowing extended gaps that could lead to data degradation, thereby maintaining both operational thoroughness and data integrity.
Solution Approach 2:
The error control operation is performed thoroughly during the first pass with results stored in buffer memory. This preliminary thorough error control, combined with immediate reuse in the second pass, ensures comprehensive data verification without extending the time gap between passes, thus maintaining data integrity while achieving thorough error control.
Data Source
AI summary
Methods, systems, and devices for multi-level cell maintenance operations are described. A controller of a memory device may perform a two-portion maintenance operation in order to transfer data from a first block of memory cells to a second block of memory cells. For example, during a first portion of the maintenance operation, the controller may read first data from the first block of memory cells and perform a first error control operation to correct the first data. The controller may store second data associated with the first error control operation to volatile memory of the memory device in response to performing the first error control operation. During a second portion of the maintenance operation, the controller may perform a second error control operation using the second data associated with the first error control operations stored to the volatile memory of the memory device.