Two-Dimensional Linked List for Storage Data Atomicity
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Solution Overview
Problem
Current solid-state data storage devices face challenges in ensuring data atomicity and consistency at low latency costs, particularly due to the rearrangement of I/O request processing orders by storage device controllers, which can introduce detrimental issues and are not effectively addressed by existing write barriers.
Innovation Solution
A two-dimensional linked list structure is employed within the storage device controller to manage block I/O requests, utilizing a hash function to associate logical block addresses with hash values, allowing for efficient processing and removal of eligible requests, thereby ensuring data atomicity and consistency while maintaining low implementation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write barriers are applied to I/O requests to ensure data atomicity and consistency, then data reliability is improved, but system performance deteriorates due to significant latency penalty
Solution Approach 1:
The patent introduces a write barrier manager as an intermediary component that sits between the I/O scheduler and the flash memory interface. This manager uses a two-dimensional linked list structure to track write barriers and their associated I/O requests, allowing the system to ensure data atomicity without requiring every I/O request to wait for barrier completion. The intermediary manages the coordination between write barriers and I/O operations, reducing the latency penalty while maintaining reliability.
Solution Approach 2:
The patent segments the I/O request processing into multiple independent chains using a two-dimensional linked list structure. Each chain represents a sequence of I/O requests that can be processed independently while maintaining atomicity guarantees. By dividing the monolithic write barrier mechanism into segmented chains, the system can process multiple I/O requests in parallel without requiring all of them to wait for barrier completion, thus reducing overall system latency while maintaining data consistency.
2Productivity
If storage device controller rearranges I/O request processing order to optimize performance, then productivity is improved, but data atomicity and consistency deteriorate due to detrimental processing issues
Solution Approach 1:
The patent implements dynamic I/O request scheduling using a write barrier manager that can adaptively rearrange I/O request processing orders based on write barrier positions and dependencies. The system dynamically determines which I/O requests can be processed out of order while maintaining atomicity guarantees, allowing flexible reordering to optimize performance without compromising data consistency. This dynamic approach enables the controller to maximize parallelism while respecting atomicity constraints.
Solution Approach 2:
The patent incorporates feedback mechanisms where the write barrier manager continuously monitors the state of I/O requests and write barriers, using this information to make intelligent scheduling decisions. The system feedback loop allows the controller to identify safe opportunities for reordering I/O requests based on completed barriers and dependency analysis, thereby improving productivity while maintaining data atomicity and consistency through informed scheduling decisions.
3Reliability
If existing write barriers are used to prevent atomicity issues, then data consistency is improved, but adaptability deteriorates because they cannot handle background operations like garbage collection
Solution Approach 1:
The patent creates a universal write barrier management system that handles multiple types of operations through a single unified mechanism. The write barrier manager and two-dimensional linked list structure are designed to manage both foreground I/O requests and background operations such as garbage collection uniformly. This multi-functional approach allows the same atomicity guarantee mechanism to serve diverse operational contexts, significantly improving adaptability while maintaining data consistency across all operation types.
Data Source
AI summary
A storage infrastructure and method for efficiently handing block I/O requests. An infrastructure is described that includes flash memory and a controller that includes: a two dimensional (2D) linked list structure for temporarily storing BIO requests, wherein each BIO request specifies a set of LBAs and wherein the 2D linked list structure includes N vertical linked lists; a BIO request loader that applies a hash function to each LBA in a received BIO request to associate each LBA to one of N hash values, and loads the received BIO request into a horizontal linked list in the 2D linked list structure in which each LBA resides within a vertical linked list based on an associated hash values; and a linked list manager that determines which LBAs in the 2D linked list structure are eligible for processing and when a horizontal linked list can be removed.