Memory Block Retirement via Transient Error Analysis
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Solution Overview
Problem
Existing memory systems face issues with excessive retirement of memory arrays due to overly conservative error detection methods, leading to reduced capacity, increased over-provisioning, and shorter life cycles.
Innovation Solution
Implementing a technique to temporarily retire memory blocks based on error detection, followed by media management operations to determine if errors are transient and correctable, allowing blocks to be re-enabled for data storage, thereby reducing premature retirement and extending system life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error detection methods are made more conservative to improve reliability, then fewer errors are detected and blocks are retired less frequently, but memory capacity is reduced and over-provisioning increases
Solution Approach 1:
The patent implements a dynamic block retirement mechanism where blocks are temporarily retired upon error detection but can be reactivated after media management operations confirm the errors were transient. This dynamic approach contrasts with static conservative retirement methods, allowing the system to adapt based on actual error characteristics rather than applying fixed retirement rules, thereby preserving memory capacity while maintaining reliability
Solution Approach 2:
The system changes the operational parameter of block availability based on error analysis results. Blocks transition between active, temporarily retired, and permanently retired states depending on whether errors are determined to be transient or uncorrectable. This parameter change approach allows flexible management of memory resources, optimizing both reliability and usable capacity by only permanently retiring blocks with confirmed permanent failures
2Reliability
If more blocks are retired to ensure data integrity, then reliability improves, but the life cycle of the memory system shortens due to reduced available capacity
Solution Approach 1:
The patent performs media management operations as a preliminary step before permanently retiring blocks. By conducting read/verify operations and analyzing error patterns in advance, the system can distinguish between transient errors that will resolve and permanent failures requiring retirement. This preliminary action prevents premature retirement of blocks that would otherwise function correctly, extending the memory system's operational life cycle while maintaining data integrity
Solution Approach 2:
The system implements feedback loops where error detection triggers media management operations, and the results of these operations feed back into the block retirement decision. Blocks are monitored continuously, and retirement status is adjusted based on ongoing error patterns and media management outcomes. This feedback mechanism ensures reliable data integrity while minimizing unnecessary retirements that would shorten system life
3Device complexity
If transient errors are not distinguished from uncorrectable errors, then simpler error handling is used, but memory capacity is wasted due to premature retirement of recoverable blocks
Solution Approach 1:
The patent segments error handling into distinct categories: transient errors, uncorrectable errors, and indeterminate errors requiring further analysis. By segmenting the error handling process and implementing different recovery strategies for each error type, the system can preserve blocks with transient errors while retiring only those with permanent failures. This segmentation approach justifies the additional complexity by significantly improving usable memory capacity through targeted rather than blanket retirement
Data Source
AI summary
Methods, systems, and devices for techniques for managing temporarily retired blocks of a memory system are described. In some examples, aspects of a memory system or memory device may be configured to determine an error for a block of memory cells. For example, a controller may determine an existence of the error and may temporarily retire the block. A media management operation may be performed on the temporarily retired block and, depending on one or more characteristics of the error, the temporarily retired block may be enabled or retired.