Linked XOR Parity Scheme for Flash Plane Failure Recovery
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Solution Overview
Problem
Flash memory devices are susceptible to failures such as program failures and silent read failures, leading to data loss and reduced reliability, with conventional designs requiring excessive flash block space for XOR parity buffers to support recovery from full plane failures with neighbor planes disturb (NPD).
Innovation Solution
A linked XOR flash data protection scheme that minimizes flash block space overhead by generating a reduced XOR parity buffer based on a full XOR parity buffer, allowing for recovery from full plane failures with NPD in a single word line, while maintaining efficient data storage and recovery capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional full die protection is implemented to support recovery from neighbor planes disturb (NPD), then data reliability is improved, but flash block space overhead increases due to extra XOR parity buffers stored in every word line
Solution Approach 1:
The patent segments the XOR parity buffer storage across multiple word lines instead of duplicating full buffers in every word line. Specifically, it divides the parity protection into segments where different word lines store different portions of the XOR parity data, reducing redundant storage while maintaining full protection capability against NPD failures.
Solution Approach 2:
The patent merges the XOR parity buffer storage across multiple word lines by implementing a distributed parity scheme. Instead of having separate full buffers in each word line, the system combines and shares parity information across word lines 0-7, reducing total storage requirements while preserving the ability to recover from full plane failures with NPD.
2Adaptability or versatility
If full XOR parity buffers are stored in every word line to enable recovery from full plane failure with NPD, then recovery capability is improved, but storage efficiency deteriorates
Solution Approach 1:
The patent transitions from a single-word-line parity buffer approach to a multi-word-line distributed parity scheme. By adding the dimension of cross-word-line parity distribution, the system achieves full plane failure recovery capability while improving storage efficiency through shared parity resources across multiple word lines.
Data Source
AI summary
Embodiments described herein provide a linked XOR flash data protection scheme for data storage devices. In particular, the embodiments described herein provide a data storage controller with a memory space efficient XOR-based flash data protection/recovery algorithm with minimal flash block space overhead and support of recovery from full plane failure with neighbor planes disturb (NPD) in a single word line. Additionally, the embodiments described herein provide a reduced flash block space dedicated for XOR parity buffers storage by a factor of a number of planes per die without losing the capability to recover from NPD.