Log Block Closure for Read Disturbance in Non-Volatile Memory
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Solution Overview
Problem
In data storage devices, read disturbance in memory cells can lead to uncorrectable error correction code (ECC) errors when new data is written to empty memory regions, causing data corruption during system updates in read-only areas.
Innovation Solution
A method is implemented to close a log block with an open word line by changing the page offset of an empty page to a page without read disturbance, either by writing dummy data to all empty pages or by assigning a new log block for updates, thereby preventing new data from being written to affected pages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If new data is written to empty memory regions in log blocks with open word lines, then the system can perform updates, but read disturbance occurs in adjacent programmed memory regions causing uncorrectable ECC errors
Solution Approach 1:
The system performs preliminary detection of read disturbance in empty memory regions before allowing write operations. The controller identifies programmed memory regions and checks adjacent empty regions for read disturbance conditions, preventing writes that would cause uncorrectable ECC errors.
Solution Approach 2:
The controller acts as an intermediary between the host and memory device, interceptating write commands destined for log blocks. It determines whether the target empty pages are adjacent to programmed pages with read disturbance, and redirects or rejects writes accordingly to prevent data corruption.
2Reliability
If the system prevents writing to empty pages with read disturbance, then data integrity is maintained, but available space for updates is reduced
Solution Approach 1:
The memory space is segmented into different types of empty pages: those safe for writing and those affected by read disturbance. The controller maintains separate tracking of these segments, allowing writes to safe regions while protecting disturbed regions, thus maximizing usable space while maintaining integrity.
Solution Approach 2:
The system changes the state parameter of log blocks from 'open' to 'closed' when read disturbance is detected in empty pages. This parameter change prevents future writes to affected pages. The controller dynamically adjusts writeable space based on read disturbance conditions, optimizing both reliability and productivity.
Data Source
AI summary
A method of operating a data storage device including a non-volatile memory device includes receiving an update command from a host; and closing a first log block, which is included in the non-volatile memory device and which includes an open word line, in response to the update command. The closing is performed to avoid update data, which is transmitted from the host and related to the update command, being subsequently written to an empty page of the first log block.