PSA Data Block Refresh Using Caches and Idle Time
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Solution Overview
Problem
Memory devices experience reduced performance due to thermal stresses during manufacturing processes, leading to errors in pre-loaded data blocks (PSA blocks) and increased read disturb stresses during access operations, which affect the overall reliability of the memory system.
Innovation Solution
A memory system that refreshes PSA blocks during access by copying data to read and write caches and utilizing a list of logical block addresses to refresh data stored in these blocks during idle durations, improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is pre-loaded into PSA blocks during manufacturing, then manufacturing efficiency is improved, but thermal stresses during attaching processes cause errors in the pre-loaded data
Solution Approach 1:
The patent performs refresh operations on PSA blocks during idle durations before normal read operations occur. By proactively refreshing the data during manufacturing or initialization phases, the system prepares the blocks to withstand subsequent thermal stresses from attaching processes, thereby maintaining data accuracy while preserving manufacturing efficiency
Solution Approach 2:
The patent implements a cushioning mechanism by creating backup copies of PSA block data in separate locations before thermal stress events occur. When thermal stresses from attaching processes threaten to cause errors, the system can revert to these pre-prepared backup copies, thus protecting data accuracy without compromising manufacturing workflow
2Reliability
If refresh operations are performed on PSA blocks, then data reliability is improved, but system performance decreases due to additional access operations
Solution Approach 1:
The patent schedules refresh operations to occur periodically during idle durations when the memory system is not actively servicing read or write requests. This periodic timing ensures that refresh operations do not compete with normal access operations for bandwidth, thereby maintaining data reliability while minimizing impact on system performance
Solution Approach 2:
The patent utilizes idle durations - periods when the memory system would otherwise be inactive - to perform refresh operations. By continuously finding productive use for idle time, the system achieves refresh coverage without extending total operation time or reducing throughput of useful access operations
3Speed
If repeated access operations are performed on PSA blocks, then data retrieval speed is improved, but read disturb stresses increase causing errors
Solution Approach 1:
The patent creates backup copies of PSA block data in separate storage locations. When read disturb stresses from repeated access operations threaten to cause errors in the original blocks, the system can retrieve data from these backup copies instead, thereby maintaining fast data retrieval speed while protecting against read disturb-induced errors
Solution Approach 2:
The patent introduces backup storage locations as intermediary copies of PSA block data. These intermediaries absorb the read disturb stresses that would otherwise directly affect the original PSA blocks, allowing repeated fast access operations to proceed while the intermediaries protect the original data integrity
4Reliability
If PSA blocks are refreshed during idle durations, then errors from thermal stresses are mitigated, but access time increases due to additional operations
Solution Approach 1:
The patent performs refresh operations during idle durations that occur before normal read access operations are initiated. By completing refresh actions in advance during these idle periods, the system ensures data reliability without adding time to subsequent access operations, as the refresh work is already done before the access request arrives
Data Source
AI summary
Methods, systems, and devices for data block refresh during read access are described. In some instances, when an access command (e.g., a read command) is received, a memory system may determine if the associated block is a PSA block. If the block is PSA block, its data may be provided to a host system to satisfy the read command and the block may either be refreshed or may be designated to be refreshed. For example, the block may be refreshed by copying its data to a write cache and writing the data from the cache to a new block. In other instances, an LBA of the block may be stored (e.g., designated) and the LBA may be refreshed when the memory system is idle.