Asymmetric RAID Parity Distribution for SSD Arrays
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Solution Overview
Problem
Current RAID 6 systems face inefficiencies in data recovery and system overheads when dealing with double disk failures, particularly in terms of capacity utilization and computational overhead during update and rebuild operations.
Innovation Solution
The proposed RAID system employs a configuration with different numbers of blocks in respective columns, utilizing row and diagonal parity blocks to optimize data recovery and update processes, allowing for efficient addition of new disks and balancing parity blocks to prevent bottlenecks, while using SSDs for improved random access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RAID 6 systems are used with uniform block distribution, then data redundancy is achieved, but system overhead increases and capacity utilization decreases during update and rebuild operations
Solution Approach 1:
The patent applies asymmetry by distributing parity blocks unevenly across columns rather than uniformly. Specifically, different columns contain different numbers of parity blocks, creating an asymmetric distribution pattern that optimizes recovery operations. This asymmetric design reduces the computational overhead during rebuild operations compared to traditional symmetric RAID 6 implementations.
Solution Approach 2:
The patent segments the RAID array into multiple columns with different block distributions. By dividing the array into columnar segments with varying parity block counts, the system can optimize recovery operations for each segment independently, reducing overall system overhead during failure recovery while maintaining data redundancy.
2Reliability
If more parity blocks are added to tolerate double disk failures, then data reliability improves, but capacity utilization decreases
Solution Approach 1:
The patent applies local quality by placing different numbers of parity blocks in different columns rather than uniformly distributing them. This allows the system to provide double disk failure tolerance (improving reliability) while concentrating parity blocks only where needed in specific columns, thereby improving overall capacity utilization compared to uniform distribution schemes.
3Productivity
If uniform block distribution is used across all columns, then system simplicity is maintained, but update and rebuild operations create bottlenecks
Solution Approach 1:
The patent resolves this contradiction by implementing asymmetric block distribution where different columns have different numbers of blocks. This asymmetric design, while slightly more complex in configuration, eliminates bottlenecks during update and rebuild operations by distributing the I/O load more effectively across the array, thereby improving productivity.
Data Source
AI summary
A redundant array of independent disk (RAID) memory storage system comprising data storage blocks arranged in a first plurality of data rows and a second plurality of data columns, wherein parity data is stored in additionally defined parity blocks, and wherein numbers of data blocks in respective columns are different, to accommodate the additional diagonal parity data block that the geometry of the system requires. The system is suitable for an SSD array in which sequential disk readout is not required.