Cluster Node Token Assignment for Tie-Breaking
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Solution Overview
Problem
In cluster systems, when the cluster interconnect fails, the reorganization process can result in multiple candidate clusters claiming to be the largest, leading to data integrity issues, and existing solutions like using a hardware tie breaker increase hardware costs and network complexity.
Innovation Solution
Assigning a token to a node in the cluster, identifying interconnected subgroups, and selecting the subgroup with the token as the cluster in case of equal sizes, using a three-phase commit protocol for token transfer and vote management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hardware element is used as a tie breaker during cluster reorganization, then a unique cluster can be selected, but hardware costs and network complexity increase
Solution Approach 1:
The patent uses a virtual token (a software-based copy or representation of authority) instead of physical hardware to resolve cluster selection conflicts. Each node maintains a copy of the token state in memory, and the token is transferred through software protocols rather than physical hardware access, eliminating the need for additional hardware while maintaining reliable cluster selection
Solution Approach 2:
The patent replaces the mechanical hardware-based tie-breaking mechanism with a software-based protocol. Instead of physically accessing a shared hardware element to determine cluster ownership, nodes use a three-phase commit protocol to exchange token information through software, substituting mechanical hardware interaction with software-based communication and logic
2Reliability
If cluster nodes use a shared hardware element for tie breaking, then data integrity is maintained, but network activity and processing complexity increase
Solution Approach 1:
The token representing cluster authority is copied and held in the memory of individual nodes rather than requiring repeated access to shared hardware. Once a node obtains the token, it can maintain cluster leadership without continuous network transactions with hardware, reducing network activity and processing overhead while preserving data integrity through the token's authoritative status
Solution Approach 2:
The token is assigned to a specific node in advance (either predetermined or through initial election), establishing cluster authority before any data access operations occur. This preliminary assignment eliminates the need for repeated hardware access during normal operations, as the token-holding node's authority is already established and recognized by other nodes
Data Source
AI summary
A method and apparatus is disclosed for selecting a cluster in a group of nodes in which a token is assigned to a first node of a group of nodes, subgroups of nodes that are interconnected are identified and if the two largest said subgroups comprise equal numbers of nodes then the subgroup containing the node to which said token is assigned is selected as the cluster.