RAID Flash Storage Layout for Metadata Separation and Data Integrity
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Solution Overview
Problem
NAND FLASH memory systems face constraints in writing data to individual pages without erasing the entire block, and managing metadata and user data efficiently, especially in RAID configurations, which affects data integrity and storage efficiency.
Innovation Solution
A method is described where a controller separates user data blocks from metadata, assembles user data blocks without metadata to occupy contiguous memory locations, and processes data to identify repeating patterns, storing metadata to optimize storage and reduce the need for writing repeating data patterns to non-volatile memory, while using error correcting codes to ensure data integrity across RAID modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metadata is stored with each user data block in traditional RAID configurations, then data integrity can be verified, but storage efficiency decreases and the number of write operations increases
Solution Approach 1:
The patent segments metadata from user data blocks, storing them in separate locations within the RAID group. This allows independent management of data and metadata, reducing the impact of metadata storage on overall storage efficiency while maintaining data integrity verification capabilities.
Solution Approach 2:
The patent extracts metadata from traditional inline storage positions and relocates it to dedicated metadata regions. This extraction reduces the overhead on user data space and allows more efficient utilization of storage capacity while preserving error detection and correction capabilities.
2Reliability
If traditional RAID storage methods are used with full-page writes, then data can be stored reliably, but memory wear increases and system longevity decreases
Solution Approach 1:
The patent changes the granularity of write operations from full-page writes to smaller, more targeted write operations. By modifying the write size parameter and allowing partial page updates, the system reduces unnecessary write amplification and extends NAND flash memory lifespan while maintaining data reliability through enhanced error correction codes.
3Reliability
If error correcting codes are implemented across RAID modules, then data integrity is improved, but computational complexity and processing time increase
Solution Approach 1:
The patent implements preliminary error detection and correction mechanisms by pre-calculating and storing error correction information alongside user data. This preliminary action allows for faster error handling during read operations, reducing real-time computational complexity while maintaining high data integrity standards across RAID modules.
Data Source
AI summary
A method of operating a memory system to compress data efficiently is described. The user data and the associated metadata are separated so that user data having repeating data patterns of greater length than a single user data structure may be assembled for storage. The user metadata and the repeating pattern metadata are stored in non-volatile memory such that the repeating pattern metadata can be used to reconstruct the repeating pattern of individual user data blocks. The reconstructed user data blocks are combined with user metadata, if any, and returned to the user in response to a read request.