RAID Controller XOR Accumulator for Synchronous Data Transfer
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Solution Overview
Problem
Current RAID disk array controllers face inefficiencies in synchronous data transfers and on-the-fly redundancy operations, particularly with evolving interfaces like UDMA and SATA, which limit performance and increase hardware complexity, especially when dealing with wide striped arrays and partial stripe updates.
Innovation Solution
A RAID disk drive controller implementing configurable data path switch logic for dynamic configuration of drives, leveraging SATA port transport layer FIFOs for synchronized data transfers, and incorporating XOR accumulator hardware to reduce buffer requirements and support narrow and wide striping modes, enabling improved performance and reduced hardware complexity through synchronous transfers and on-the-fly redundancy operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If synchronous data transfers are implemented with evolving interfaces like UDMA and SATA, then data transfer performance is improved, but hardware complexity increases
Solution Approach 1:
The patent combines multiple data transfer operations into a single synchronous transfer sequence. The controller issues read commands to multiple drives simultaneously and aggregates their data streams through a merge mechanism, achieving high-speed data transfer without requiring separate complex hardware paths for each drive.
Solution Approach 2:
The controller implements a universal interface layer that handles both UDMA and SATA protocols through a common architecture. The synchronous transfer mechanism works across different interface types, reducing the need for interface-specific hardware complexity while maintaining high performance.
2Productivity
If on-the-fly redundancy operations are implemented, then RAID performance is improved, but buffer requirements increase
Solution Approach 1:
The controller performs preliminary data aggregation and preprocessing before redundancy operations are needed. By maintaining a streamlined data flow path and pre-positioning data in the transfer stream, the system enables on-the-fly XOR operations without requiring large intermediate buffers.
Solution Approach 2:
The patent introduces a dedicated redundancy calculation unit that acts as an intermediary in the data stream. This unit performs XOR operations directly on the flying data streams from multiple drives, eliminating the need to buffer complete data sets before redundancy processing.
3Power
If wide striped arrays are configured, then sustained bandwidth is improved, but access time increases
Solution Approach 1:
The controller segments the wide striped array into multiple independent data streams that can be processed concurrently. Each stream handles a portion of the total data width, allowing the system to achieve high sustained bandwidth while maintaining low latency through parallel processing of segmented data paths.
Data Source
AI summary
A RAID disk drive controller (FIG. 33) implements disk storage operations, including striping and redundancy operations with multiple disk drives connected via respective SATA ports (520). Configurable data path switch logic (460) provides dynamic configuration of two or more attached drives into one or more arrays. Data transfers are synchronized locally by leveraging the SATA port transport layer FIFO (530). Synchronous transfers allow on-the-fly redundancy (XOR) operations (FIG. 36) for improved performance and reduced hardware complexity. XOR accumulator hardware (FIG. 42-FIG. 43) reduces buffer requirements for multiple DMA channels otherwise required for synchronization, and various narrow and wide striping modes are supported.