Memory Controller Write Scheduling With Overlapped Read-Verify
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Solution Overview
Problem
The read-and-verify operation in nonvolatile memory systems increases the time required for data write operations, necessitating more efficient data write methods.
Innovation Solution
The controller executes a read-and-verify operation for selected pages before writing new data, overlapping the read-and-verify process with data transfer from the host, allowing parallel execution of these operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a read-and-verify operation is executed after data write to ensure data integrity, then data reliability is improved, but write operation time increases
Solution Approach 1:
The patent applies preliminary action by executing read-and-verify operations on selected pages before the data write operation completes. The controller selects pages from the block and performs verification in advance, so that when the write operation finishes, the verification is already underway or completed, thereby reducing the total time without compromising data integrity.
Solution Approach 2:
The patent implements continuity of useful action by overlapping the read-and-verify operation with the data write operation. The controller continuously performs verification on selected pages during the write process, ensuring that verification actions are ongoing and not idle, thus maximizing system efficiency while maintaining reliability.
2Reliability
If read-and-verify operation is performed sequentially after data write, then data reliability is ensured, but write efficiency decreases
Solution Approach 1:
The controller performs read-and-verify operations on selected pages before the data write operation is fully completed. By preparing and verifying pages in advance, the system ensures data reliability while avoiding sequential processing delays, thereby maintaining high write efficiency.
Solution Approach 2:
The patent introduces a dimensional change by selecting and verifying pages based on their position within the block rather than processing all pages sequentially. The controller selects pages from the block and performs verification in a distributed manner across different pages, transforming a one-dimensional sequential process into a multi-dimensional parallel process, which improves both reliability and efficiency.
Data Source
AI summary
According to one embodiment, a memory system includes a nonvolatile memory including physical blocks, and a controller. Upon receiving a write command from a host, the controller starts to receive first data associated with the write command; selects one of a plurality of first pages, the plurality of first pages being physical pages to which second data has already been written and for which no read-and-verify operation has been executed; executes a read-and-verify operation for the selected one of the plurality of first page; and writes the received first data to a second page in a write destination block among the physical blocks.