RAID Data Multiplication Using XOR Map Tables for Fast Parity
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Solution Overview
Problem
Current RAID systems face inefficiencies in data multiplication operations due to the need for extensive table lookups and calculations, which become bottlenecks as storage sizes increase, especially in RAID6 systems requiring multiple parity calculations.
Innovation Solution
The implementation of a method and controller that generate map tables for Galois Field operations, allowing for simultaneous XOR operations using enlarged XOR operation units, thereby simplifying and speeding up data multiplication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional table lookup methods are used for Galois Field multiplication in RAID6 systems, then correctness of parity calculation is ensured, but computation speed deteriorates due to extensive table lookups and calculations
Solution Approach 1:
The patent pre-calculates and stores multiplication results in map tables during system initialization, so that during RAID6 parity operations, the controller can directly retrieve pre-computed values instead of performing time-consuming Galois Field multiplication calculations, thus resolving the contradiction between computational correctness and speed
Solution Approach 2:
The patent performs multiplication operations on enlarged data units (e.g., 64-bit or 128-bit units) rather than individual bytes, using partial map tables that cover only the necessary range of operations. This reduces the total number of table lookups required while maintaining correctness, thereby improving computation speed
2Quantity of substance
If storage size increases in RAID systems, then capacity is improved, but the bottleneck of table lookup operations becomes more severe
Solution Approach 1:
The patent transitions from byte-level operations to enlarged unit operations (64-bit, 128-bit, or larger), effectively adding a dimension to the data processing. This allows parallel processing of multiple bytes simultaneously, reducing the time penalty associated with larger storage capacities that require more multiplication operations
3Reliability
If multiple parity calculations are performed in RAID6, then fault tolerance is improved, but the complexity of multiplication operations increases
Solution Approach 1:
The patent pre-computes and stores all necessary multiplication results for both P and Q parity calculations in map tables during system initialization. This eliminates the need to perform complex Galois Field multiplication operations during actual parity generation or data recovery, thereby reducing operational complexity while maintaining dual-parity fault tolerance
Solution Approach 2:
The patent creates simplified copies of multiplication results in map tables that can be directly used during parity operations. Instead of implementing complex Galois Field multiplication logic during runtime, the system uses pre-computed lookup tables that simplify the operational complexity while preserving the mathematical correctness required for multiple parity calculations
Data Source
AI summary
The invention discloses a method and controller for processing data multiplication in a RAID system. Map tables are generated for all values in a field, respectively. The length of an XOR operation unit is chosen to be appropriate w bits (e.g., 32 bits or 64 bits). One or several XOR operation units form a multiplication unit of a data sector. When computing on-line, data in a disk drive of a disk array are performed with XOR operations in accordance with one of the map tables using an XOR operation unit as one unit while computing on the multiplication unit to obtain a product of multiplication.Making use of the RAID system established according to the disclosed method, only XOR operations are required to compute parity data or recover damaged user data. Moreover, several calculations can be performed simultaneously. Therefore, the efficiency of the RAID system can be effectively improved.