Controller-Based ECC for NAND Flash Copy-Back
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Solution Overview
Problem
NAND flash memory devices do not perform error correction during copy-back operations, leading to error propagation and inefficiencies in data transfer between the host and the memory device.
Innovation Solution
A controller is introduced to receive data and error correction codes from the NAND flash memory device, check for errors, and correct them before writing the data to a new location, ensuring accurate data transfer and reducing the need for redundant communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the NAND flash memory device performs copy-back operation without ECC checking, then the communication bus is avoided and processing overhead is reduced, but errors in the data are propagated
Solution Approach 1:
The patent introduces a controller as an intermediary component between the host and the NAND flash memory device. The controller performs ECC checking and error correction on data during copy-back operations, while the memory device itself remains free to perform high-speed copy-back operations without ECC overhead. This mediator approach allows the system to achieve both high productivity (through fast copy-back) and high reliability (through controller-based error correction).
Solution Approach 2:
The patent implements preliminary ECC checking by the controller before data is copied within the memory device. The controller reads data from the source address, performs error correction code verification and correction, then writes the corrected data to the destination address. This preliminary action ensures data accuracy is maintained while preserving the speed benefits of copy-back operations.
2Reliability
If standard read and program operations are used to move data, then error correction can be performed, but the communication bus is occupied and host processing overhead increases
Solution Approach 1:
The controller serves as an intermediary that handles ECC checking and error correction, allowing the memory device to perform optimized copy-back operations. This separation of concerns enables the memory device to focus on high-speed data movement while the controller ensures data integrity, achieving both reliability and productivity simultaneously.
Solution Approach 2:
The patent utilizes the copy-back command to create an internal copy of data within the memory device without involving the host system. This internal copying mechanism, managed by the controller, eliminates the need for host intervention and communication bus transactions, thereby maintaining high data transfer efficiency while ensuring error correction through the controller's ECC capabilities.
3Reliability
If the host performs error correction, then data accuracy is maintained, but host processing power and overhead are consumed
Solution Approach 1:
The controller acts as an intermediary that offloads error correction functionality from the host system. By implementing ECC checking and correction in the controller, the patent eliminates the need for host processing power to be dedicated to error correction, thereby maintaining data accuracy while reducing host processing burden and system complexity.
Solution Approach 2:
The controller performs error correction autonomously during copy-back operations without requiring host intervention. This self-service approach allows the system to maintain data accuracy through automatic ECC checking and correction, freeing the host from processing overhead while ensuring reliable data transfer.
Data Source
AI summary
The embodiments described herein provide a method and controller for performing a copy-back command. In one embodiment, a controller receives the data and error correction code associated with a copy-back operation from at least one flash memory device. The controller determines if the error correction code indicates there is an error in the data. If the error correction code does not indicate there is an error in the data, the controller sends a destination address and copy-back program command received from a host to the at least one flash memory device. If the error correction code indicates there is an error in the data, the controller corrects the data and sends the destination address, the corrected data, and a program command to the at least one flash memory device. Additional embodiments relate to modifying data during the copy-back operation.