Storage Controller Copy-Back Selection for Efficient Page Migration
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Solution Overview
Problem
Data movement in non-volatile memory devices, such as data migration from a single level cell (SLC) to a triple level cell (TLC) area, is inefficient due to the need for error detection and correction operations, which prolongs the time required for data output and transmission, thereby reducing performance.
Innovation Solution
A method involving a storage controller that selects a representative page, performs error detection, and based on the error bit threshold, executes either an internal or external copy-back operation to optimize data movement by minimizing unnecessary data transmission and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error detection and correction operations are performed for all data during migration, then data reliability is improved, but data movement time increases
Solution Approach 1:
The patent applies preliminary action by performing error detection on a representative page before migrating the entire group of pages. The storage controller selects a representative page from each group, detects errors in advance, and determines the error status of all other pages in the group based on this preliminary detection, thereby avoiding time-consuming error detection and correction operations for all pages during data migration.
Solution Approach 2:
The patent uses copying by migrating data in group units rather than individual page units. Multiple pages with similar error characteristics are copied together as a group, and the error detection result of one representative page is applied to copy the error status to all other pages in the group, reducing redundant error detection and correction operations.
2Reliability
If data is migrated page by page with full error correction, then error correction completeness is improved, but migration efficiency deteriorates
Solution Approach 1:
The patent applies segmentation by dividing pages into groups based on their error characteristics and processing them in group units rather than individually. Pages are segmented into groups where a representative page is selected for error detection, and the results are applied to all pages in the group, reducing the total number of error detection and correction operations while maintaining completeness.
Solution Approach 2:
The patent applies universality by making the error detection result of a representative page universally applicable to all pages in the same group. The error status determined from one representative page is used to guide error correction for all other pages in the group, allowing a single detection operation to serve multiple pages and improving migration efficiency.
3Loss of time
If representative page error detection is used to determine copy-back operation type, then unnecessary data transmission is reduced, but operation complexity increases
Solution Approach 1:
The patent applies preliminary action by determining the copy-back operation type in advance based on error detection of a representative page. The storage controller performs error detection on the representative page before data migration, determines whether external or internal copy-back is needed, and prepares the appropriate operation mode beforehand, avoiding unnecessary data transmission and reducing actual migration time.
Data Source
AI summary
A method includes selecting, by a storage controller, a representative page of a first group stored in a first area included in a non-volatile memory device; receiving, by the storage controller, the representative page from the non-volatile memory device; performing, by the storage controller, an error detection operation of determining a number of error bits for the representative page; based on determining that the number of error bits of the representative page exceeds a threshold value, performing an external copy-back operation, by the storage controller, for each page of the first group to a second area included in the non-volatile memory device; and based on determining that the number of error bits of the representative page is less than or equal to the threshold value, performing an internal copy-back operation, by the storage controller, for each page of the first group to the second area.