Cluster Resource Fencing via Quorum Validation
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Solution Overview
Problem
Current solutions for managing access to shared resources in a computer cluster lack a general approach, being tightly coupled to specific I/O system requirements, and do not effectively handle fencing interactions between nodes.
Innovation Solution
Implementing a method that verifies the validity of a quorum before enforcing access rights, using quorum generation numbers and challenge-commands to ensure only valid quorum groups access shared resources, with software agents mediating access and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current fencing solutions are implemented, then access control to shared resources is achieved, but the system lacks generality and is tightly coupled to specific I/O system requirements
Solution Approach 1:
The patent implements a universal fencing mechanism that works across different I/O systems and storage devices. The fencing interface defines a standardized set of operations (fence, unfence, check, etc.) that can be applied to any shared resource regardless of the underlying I/O system. This allows the same fencing logic to be used for SCSI devices, network-attached storage, and other shared resources, eliminating the need for I/O-system-specific fencing implementations.
2Reliability
If quorum-based access control is enforced without validation, then access rights are maintained, but invalid quorums may cause unauthorized access or system instability
Solution Approach 1:
The patent performs quorum validation before enforcing access rights. When a node presents a quorum token claiming authority to access shared resources, the system first validates the token's authenticity and the quorum's current validity state before allowing access. This preliminary validation prevents unauthorized access from nodes with stale or invalid quorum information, ensuring that only currently authorized nodes can access shared resources.
Solution Approach 2:
The fencing mechanism implements feedback loops where nodes continuously report their quorum status and the system verifies this information. The check operation allows nodes to query the current state of fencing tokens and validate their quorum membership. This feedback mechanism ensures that nodes have accurate information about which nodes are authorized to access shared resources, preventing split-brain scenarios and maintaining system consistency.
3Reliability
If fencing operations are performed without verification, then access control speed is maintained, but unauthorized nodes may access shared resources
Solution Approach 1:
The system performs critical validation checks before executing fencing operations. Before a node is fenced out or a fencing token is issued, the system verifies the requesting node's authority, the validity of the quorum, and the current state of fencing tokens. This preliminary verification ensures that fencing operations are secure and authoritative, preventing unauthorized access control while maintaining system reliability.
Data Source
AI summary
Techniques are provided for managing access to resources that are shared by a cluster of nodes. One aspect of the invention is to require verification that a quorum is a valid quorum prior to enforcing the access rights specified by a node that is a member of the group of nodes holding the quorum. Further, the verification that a quorum is a valid quorum prior to enforcing access rights occurs only if the quorum associated with the specified access rights is suspected to be invalid.