Read Cache Failover via Asynchronous Data Copying
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Solution Overview
Problem
Existing data storage systems face challenges in maintaining high-speed read caching performance and fault tolerance, particularly in scenarios where storage controllers fail, leading to disruptions in read cache availability across multiple controllers.
Innovation Solution
The implementation of a method that maintains first and second read caches controlled by separate storage controllers, with data being copied and processed for failover, utilizing flash memory for non-volatile caching to ensure seamless transitions and reduce power consumption, and employing compression techniques to asynchronously transfer and decompress read cache data across controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple storage controllers are used to provide fault tolerance and higher throughput, then system reliability and throughput are improved, but device complexity and data management difficulty increase
Solution Approach 1:
The read cache is divided into separate read cache data structures maintained by different storage controllers. Each controller manages its own cache independently, reducing the complexity of coordinating data between multiple controllers while maintaining fault tolerance. The segmentation allows each controller to operate autonomously without requiring complex inter-controller synchronization.
Solution Approach 2:
Read cache data is copied from a first storage controller to a second storage controller to ensure data availability if the first controller fails. This copying mechanism provides fault tolerance by creating redundant copies of critical data, allowing the system to continue operating with reduced performance but maintaining reliability without requiring complex real-time synchronization protocols.
2Reliability
If read cache data is replicated across multiple storage controllers to ensure availability during failures, then system reliability is improved, but bandwidth consumption and data transfer overhead increase
Solution Approach 1:
Read cache data is replicated to the second storage controller in advance before a failure occurs. This preliminary copying action ensures that when the first controller fails, the second controller already has the necessary data to continue serving read requests, eliminating the need for urgent data transfer during failure events and reducing overall bandwidth consumption.
Solution Approach 2:
The system copies read cache data from one controller to another as a background operation rather than requiring continuous real-time synchronization. This selective copying approach replicates only necessary data while minimizing bandwidth consumption, achieving reliability without excessive energy expenditure on data transfer.
3Reliability
If storage controllers continuously synchronize read cache data to maintain consistency, then data availability is improved, but processing time and system latency increase
Solution Approach 1:
The system performs data synchronization in advance during normal operation rather than continuously. By copying read cache data to the second controller as a preliminary action, the system ensures data availability without requiring continuous synchronization, thereby reducing latency and improving response time while maintaining reliability.
Data Source
AI summary
A method is used in managing read caching. First and second read caches are maintained in a data storage system. The first read cache is controlled by a first storage controller and the second read cache is controlled by a second storage controller. Read cache data is copied from the first storage controller to the second storage controller. A failure of the first storage controller is detected. Based on the detection, the copied read cache data is processed at the second storage controller to make the copied read cache data available for use at the second storage controller.