RAID Memory Read Latency Reduction via Dual Parity Validation
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Solution Overview
Problem
Current RAID systems face latency issues during read operations due to the need to wait for all disk drives to complete a command, which limits data transfer rates and degrades as disk drives fail, while methods to reduce latency often compromise data integrity.
Innovation Solution
A method that utilizes a dual parity generation engine to identify and reconstruct valid data from N−1 disk storage channels, allowing data transfer to proceed without waiting for the lagging Nth disk drive, while ensuring data integrity by verifying the integrity of data from N−1 channels and waiting for all channels if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system waits for all N disk drives to complete a read command before transferring data, then data integrity is ensured, but data transfer rate is limited and latency increases
Solution Approach 1:
The system performs preliminary integrity checking on data from N-1 disk drives before the Nth drive completes its operation. By checking data validity in advance using parity information, the system can begin transferring valid data immediately without waiting for all drives, thus improving data transfer rate while maintaining integrity through preliminary validation
Solution Approach 2:
The system segments the data transfer process into two independent paths: (1) transfer data from N-1 drives after integrity verification, and (2) continue receiving data from the Nth drive. This segmentation allows parallel processing where valid data is transferred immediately while the remaining data is still being retrieved, eliminating the bottleneck of waiting for all drives
2Productivity
If the system transfers data from N-1 disk drives before integrity checking, then latency is reduced, but data integrity cannot be ensured
Solution Approach 1:
The system performs integrity checking using parity information from the N-1 drives immediately after their data arrives, before the Nth drive completes. This preliminary validation enables the system to confirm data validity in advance, allowing immediate transfer of verified data without compromising integrity, thus achieving both low latency and high reliability
Solution Approach 2:
The system uses parity information as feedback to validate data from N-1 drives in real-time. By continuously monitoring data integrity through parity checks and receiving feedback on validation results, the system can dynamically determine when data is valid and proceed with transfer, ensuring integrity while minimizing waiting time
Data Source
AI summary
A latency reduction method for read operations of an array of N disk storage devices (210) having n disk storage devices (210A-210H) for data storage and p of disk storage devices (210I, 210J) for storing parity data is provided. Utilizing the parity generation engine's (230) fault tolerance of for a loss of valid data from at least two of the N disk storage devices (210A-210J), the integrity of the data is determined when N−1 of the disk storage devices (210A-210J) have completed executing a read command. If the data is determined to be valid, the missing data of the Nth disk storage device is reconstructed and the data transmitted to the requesting processor (10). By that arrangement the time necessary for the Nth disk storage device to complete execution of the read command is saved, thereby improving the performance of memory system (200).