Multi-Layer ECC Copyback Between SLC and QLC Partitions
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Solution Overview
Problem
Existing memory devices face inefficiencies due to a mismatch in error correction needs between SLC and QLC modes, leading to wasted storage space and reduced endurance in SLC blocks, especially during copyback operations.
Innovation Solution
Implementing a multi-layer code rate architecture that splits parity data into two parts, with one part stored within SLC blocks and another part available externally for higher error correction, allowing efficient copyback operations between SLC and QLC partitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction code is used with high code rate for SLC blocks to ensure data reliability, then error correction capability is improved, but storage capacity is reduced due to increased parity bits
Solution Approach 1:
The error correction code is segmented into two parts: a first error correction code stored within the SLC block and a second error correction code stored externally. This segmentation allows the SLC block to contain only essential error correction data, improving storage capacity while maintaining reliability through the combined two-layer error correction system.
2Productivity
If copyback operation is implemented between SLC and QLC partitions, then data transfer efficiency is improved, but error correction mismatch causes data integrity issues
Solution Approach 1:
The first error correction code stored in the SLC block acts as an intermediary that enables direct copyback operations between SLC and QLC partitions. This intermediary error correction code allows data to be transferred efficiently while maintaining integrity, as it provides sufficient error correction capability for the copyback operation without requiring full QLC-level error correction.
3Reliability
If SLC blocks use higher error correction overhead to match QLC error correction needs, then data reliability is improved, but SLC block endurance is reduced due to increased write amplification
Solution Approach 1:
Different error correction strategies are applied to different data access patterns. SLC blocks use a lightweight first error correction code for frequent write operations, preserving endurance. QLC partitions use a more robust second error correction code for less frequent access. This local quality differentiation optimizes both reliability and endurance for each storage medium's characteristics.
Data Source
AI summary
Systems, methods, and apparatus related to a multi-level error correction architecture used for copying data in memory devices. In one approach, user data is stored in the first partition of a non-volatile memory. First error correction code data is generated for the user data and stored with the user data in the first partition. Second error correction code data is generated for the user data and stored outside the first partition. The second error correction code data provides an increased error correcting capability that is compatible with the error correction algorithm used with the first error correction code data. A copyback operation is used to copy the user data and the first error correction code, but not the second error correction code, to a second partition of the non-volatile memory. The second error correction code can be selectively used if there is a need to recover portions of the user data stored in the first partition.