RAID Data Recovery Using Correlated Reference Codewords
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high-density data storage devices, achieving a very low bit error rate is challenging despite the use of error correction codes like turbo codes or LDPC codes, necessitating an effective data recovery technique.
Innovation Solution
A method involving the use of codewords with code correlation to read reference codewords from a memory device, generate a corrected decoder input, and perform error-correcting code decoding again to recover the target codeword, especially in RAID storage systems and nonvolatile memory systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turbo code or LDPC code is used for error correction in high-density memory devices, then error correction capability is improved, but bit error rate cannot achieve the very low level required by the system
Solution Approach 1:
The patent performs preliminary actions by reading and decoding reference codewords that have code correlation with the target codeword before attempting to decode the target codeword itself. When the target codeword decoding fails, the previously decoded reference codewords are used to generate a corrected decoder input, thereby preparing a corrected version before the final decoding attempt.
Solution Approach 2:
The patent introduces reference codewords as intermediaries between the target codeword and the decoding process. These reference codewords, which have code correlation with the target codeword, serve as mediators to help recover the target codeword when direct decoding fails, bridging the gap between the failed decoding attempt and successful recovery.
2Speed
If conventional ECC decoding is used when decoding fails, then decoding speed is maintained, but data recovery success rate is low
Solution Approach 1:
The system performs preliminary decoding on reference codewords that have code correlation with the target codeword. When the target codeword decoding fails, these pre-decoded reference codewords are immediately available to generate a corrected decoder input, avoiding the need to start decoding from scratch and thus maintaining speed while improving recovery success rate.
Solution Approach 2:
The patent implements a feedback mechanism where the decoding result of the target codeword is monitored, and when decoding fails, the system feeds back to use reference codewords to generate a corrected decoder input. This feedback loop allows the system to adaptively switch to an alternative decoding path when conventional decoding fails, improving overall recovery success rate.
3Measurement precision
If reference codewords with code correlation are read and used for correction, then data recovery accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent segments the decoding process into distinct phases: decoding reference codewords first, then decoding the target codeword, and finally using reference codeword results to correct target codeword decoding failures. This segmentation allows the system to handle complex recovery tasks in manageable steps, improving accuracy while making the complexity more controllable.
Solution Approach 2:
The reference codewords serve multiple functions: they are decoded independently to provide backup information, used to generate corrected decoder inputs when target decoding fails, and leverage code correlation to improve recovery accuracy. This multi-functionality justifies the additional processing complexity by providing multiple benefits from the same reference codeword mechanism.
Data Source
AI summary
A method and system of recovering data includes reading reference codewords, which have code correlation with a target codeword, from a memory device when an error-correcting code (ECC) decoding process for a decoder input of the target codeword has failed. A decoder input of a corrected target codeword is generated based on an operation process using the target codeword and the reference codewords. An ECC decoding process is performed again on the decoder input of the corrected target codeword.