Flash Memory Controller Low Latency Copy Operations
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Solution Overview
Problem
The process of copying data in flash memory devices, such as during garbage collection, introduces significant latency due to errors in the data that need to be corrected, which can propagate and further introduce errors, affecting the performance and speed of non-volatile memory devices like SSDs.
Innovation Solution
Implementing a method where the flash memory controller estimates error locations using ECC algorithms and sends information identifying these errors for error-fixing, allowing corrected data to be stored in a second set of locations using a modified copy back command, reducing the need for extensive error correction during data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is copied from first set of locations to second set of locations during garbage collection, then data recycling is achieved, but latency increases due to error correction requirements
Solution Approach 1:
The patent applies preliminary action by performing error location estimation using ECC algorithms on the source data before the copy operation begins. The flash memory controller identifies and marks error locations in advance, then sends correction information to the destination along with the data. This allows the destination to perform targeted error fixing only at identified locations rather than processing the entire data set, significantly reducing the time required for error correction during data copying while maintaining data integrity.
2Measurement precision
If extensive error correction is performed during data transfer, then data accuracy is improved, but processing time increases
Solution Approach 1:
The patent implements local quality by transitioning from global error correction (processing entire data blocks) to localized error correction (processing only specific error-prone locations). The flash memory controller estimates error locations using ECC algorithms and sends correction information pinpointing exact positions that need fixing. The destination applies corrections only at these specific locations rather than reprocessing all data, thereby maintaining high error detection accuracy while dramatically improving data copying speed.
Solution Approach 2:
The patent extracts only the essential error correction information needed for fixing data errors, rather than transferring and processing complete error correction datasets. The flash memory controller identifies error locations and sends compact correction information (location addresses and correction values) to the destination. This extracted approach maintains measurement precision for error detection while reducing productivity loss by minimizing the amount of data requiring correction processing.
3Ease of operation
If traditional copy back commands are used, then data is transferred between locations, but performance is degraded due to error handling overhead
Solution Approach 1:
The patent applies parameter changes by modifying the traditional copy back command protocol to include error location estimation results and correction information. Instead of using standard copy back commands that transfer raw data without error context, the system enhances the command structure to carry pre-computed error location data and correction parameters. This allows the flash memory controller to maintain ease of operation with familiar copy back semantics while dramatically improving garbage collection performance through pre-processing error information that enables fast targeted corrections at the destination.
Data Source
AI summary
Techniques and systems are provided for copying, with or without error-fixing or corrections, data associated with a first set of locations to a second set of locations in a flash memory. Example methods disclosed, when performed by a flash memory controller, can significantly improve latency of operations. Embodiments of the disclosure can be used, for example, in a garbage collection process of a NAND flash memory.