Quiescing Protocol Coordinator for Distributed System Consistency

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Solution Overview

Problem

Distributed architecture systems face challenges in ensuring that all messages are processed before reintegrating a failed node, leading to potential system state destruction or unnecessary delays during quiescing protocols.

Innovation Solution

A quiescing protocol is implemented, where a coordinator initiates the process by sending start messages, tracking message processing through counters, and verifying that all messages have been processed through probe messages and checkpoints, ensuring a consistent system state without unnecessary delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a quiescing protocol is implemented to ensure all messages are processed before reintegrating a failed node, then system reliability is improved, but the duration of the quiescing process increases causing unnecessary delays

Engineering Contradiction:

Improvesystem consistencyVSAvoidquiescing duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The coordinator sends probe messages to all nodes before initiating the full quiescing protocol to determine which nodes are alive and ready. This preliminary action allows the system to skip unnecessary quiescing steps for already-responsive nodes, reducing overall quiescing duration while maintaining consistency guarantees for all nodes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The quiescing protocol dynamically adjusts its behavior based on node responses. Nodes that respond quickly to probe messages can proceed with normal operations while the coordinator continues monitoring, whereas nodes that do not respond trigger full quiescing procedures. This dynamic approach optimizes the balance between reliability and time loss.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If the quiescing protocol suspends new messages to ensure processing completion, then system state consistency is maintained, but productivity decreases due to message processing delays

Engineering Contradiction:

Improvesystem state consistencyVSAvoidmessage processing throughput

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The quiescing protocol segments the message processing into distinct phases: probe phase (checking node availability), checkpoint phase (verifying message processing), and resumption phase (allowing new messages). During the checkpoint phase, new messages are temporarily suspended, but the protocol efficiently transitions to resumption once consistency is verified, minimizing overall productivity impact.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coordinator receives feedback from nodes about their message processing status through checkpoint messages. This feedback mechanism allows the coordinator to make informed decisions about when to resume message processing, ensuring that suspension only occurs when necessary and for the minimum duration required to achieve consistency.

Inventive Principle:

Principle #23Feedback

3Reliability

If the system waits for all nodes to confirm message processing before reintegrating a failed node, then system consistency is ensured, but the time to restore system functionality increases

Engineering Contradiction:

Improvesystem consistencyVSAvoidnode reintegration time

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The coordinator performs preliminary probe messages to all nodes before initiating full quiescing to identify which nodes are responsive. This allows the coordinator to target quiescing only at nodes that actually need it, rather than waiting for all nodes to confirm processing, thereby reducing reintegration time while maintaining consistency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protocol applies partial quiescing by only suspending new messages at nodes that are determined to be unresponsive or potentially inconsistent during the probe phase. Responsive nodes can proceed with normal operations, reducing the overall duration of the reintegration process while still ensuring consistency where needed.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7848261B2Systems and methods for providing a quiescing protocol

Publication Date: 2010.12.07 EMC IP HLDG CO LLC

AI summary

The systems and methods of the present invention provide a quiescing protocol. In one embodiment, nodes of a system utilize the protocol to complete processing until they reach a consistent state. In one embodiment, a coordinator initiates the quiescing process and the nodes communicate with each other to determine whether their messages have been processed and communicate with the coordinator to determine when all of the messages have been processed.