Targeted Post-Write Read for Valid NAND Update Blocks
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Solution Overview
Problem
Conventional enhanced post-write read (EPWR) methods in NAND flash devices perform operations on all wordlines regardless of data validity, leading to inefficient use of secondary blocks and reduced performance due to the retention of invalid data, which increases the need for additional storage and affects block budget.
Innovation Solution
Implement a targeted enhanced post-write read (EPWR) method that identifies and selectively performs operations on valid data regions, releasing secondary blocks when no uncorrectable errors are detected, and performs a secondary operation on invalid regions as a background process to manage defective blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EPWR is performed on all wordlines regardless of data validity, then data integrity is ensured, but device performance deteriorates and block budget is negatively impacted
Solution Approach 1:
The patent segments the wordlines into valid and invalid categories based on data validity status. EPWR operations are selectively applied only to valid wordlines, while invalid wordlines are excluded from the verification process. This segmentation resolves the contradiction by maintaining data integrity for valid data while eliminating unnecessary operations on invalid data, thereby improving device performance and block budget utilization.
2Reliability
If conventional EPWR is performed on all wordlines, then comprehensive error detection is achieved, but secondary block retention increases
Solution Approach 1:
The patent extracts and identifies invalid wordlines from the block, separating them from valid wordlines. By taking out the invalid wordlines that do not require verification, the system can release secondary blocks more aggressively without compromising error detection for valid data. This extraction principle resolves the contradiction by maintaining comprehensive error detection where needed while reducing secondary block retention overall.
3Reliability
If conventional EPWR processes all wordlines sequentially, then thorough verification is completed, but processing time increases
Solution Approach 1:
The patent applies partial action by performing EPWR only on valid wordlines rather than all wordlines. Since invalid wordlines do not contain meaningful data requiring verification, the system performs the minimum necessary EPWR operations to ensure data integrity. This partial action principle resolves the contradiction by maintaining verification thoroughness for valid data while significantly reducing overall processing time.
Data Source
AI summary
Examples include a data storage device controller with one or more electronic processors configured to receive a write command that includes host data to be written to a memory, and service the write command by controlling the memory to write the host data to a primary update block of the memory and a secondary update block of the memory. The one or more electronic processors perform a first targeted enhanced post-write read (EPWR) operation on the primary update block by identifying one or more valid data regions of the primary update block, selectively performing EPWR on the one or more valid data regions of the primary update block, and in response to determining, based on a result of the EPWR performed on the one or more valid data regions, that the one or more valid data regions do not include an uncorrectable error, releasing the secondary update block.