Cluster Failover via Replay Queue for Network Partitioning
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Solution Overview
Problem
Cloud-based computer systems face challenges in synchronizing the dynamic changes of access point configurations between primary and backup controllers, leading to difficulties in providing reliable redundant support, especially due to failures in the computer system or network.
Innovation Solution
Implementing a synchronization technique that involves a primary cluster with a replay queue to store and playback configuration requests for a backup cluster, ensuring seamless failover coverage even when primary or backup controllers fail, and maintaining synchronization during link failures by storing and replaying configuration requests when the link is restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backup controller is implemented to provide redundant support, then reliability is improved, but difficulty in synchronizing dynamic configuration changes increases
Solution Approach 1:
The system performs preliminary actions by maintaining a replay queue that stores configuration changes before they are needed for failover. When the primary controller is operational, configuration changes are captured and stored in the replay queue, preparing the backup controller in advance so that it can immediately assume the current configuration state without synchronization delays during failover events.
Solution Approach 2:
The system creates a copy of the primary controller's configuration state by replaying stored configuration requests on the backup controller. Instead of continuously synchronizing the entire state, the backup controller receives and executes copied configuration commands from the replay queue, maintaining configuration parity with the primary controller while reducing synchronization complexity.
2Measurement precision
If configuration requests are continuously synchronized in real-time, then synchronization accuracy is improved, but network bandwidth consumption increases
Solution Approach 1:
The system extracts only the essential configuration change commands from the primary controller and stores them in the replay queue for later replay on the backup controller. Instead of continuously transmitting all configuration data or maintaining constant real-time synchronization, the system extracts and transmits only the necessary configuration requests when changes occur, reducing network bandwidth consumption while maintaining synchronization accuracy.
3Reliability
If the backup cluster is kept fully synchronized with the primary cluster, then failover reliability is improved, but device complexity increases
Solution Approach 1:
The replay queue serves as an intermediary mechanism between the primary and backup controllers. Configuration changes are captured in the replay queue during normal operation, and the backup controller replays these stored commands to maintain synchronization. This intermediary approach simplifies the backup cluster's complexity by providing a structured, event-driven synchronization mechanism rather than requiring complex continuous synchronization protocols.
Data Source
AI summary
During a synchronization technique, states of a primary cluster in the computer system with multiple primary controllers that provide controllers for access points and a backup cluster in the computer system with multiple backup controllers that independently provide controllers for the access points may be dynamically synchronized. In particular the primary cluster may receive configuration requests with configuration information for the access points on an input node of the primary cluster. In response, the primary cluster may store the configuration requests in a replay queue in the computer system. Then, the primary cluster may playback the configuration requests in the replay queue for the backup cluster to synchronize the states of the primary cluster and the backup cluster. For example, the configuration requests may be played back within a time interval associated with a service level agreement of a service provider of a service for the access points.