Relative Reference Updates for Virtual Machine Volume Chains
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
When unlinking volumes from a volume chain in a virtual machine, maintaining relative references is challenging, especially in shared storage environments, as absolute references can become invalid upon host changes or storage path modifications, leading to VM unavailability.
Innovation Solution
The solution involves defining relative references for volumes within the volume chain, ensuring that when a volume is removed, its child volumes maintain a relative path to the parent volume, allowing the virtual machine to operate across different hosts and storage paths by updating references to maintain consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If absolute references are used for volumes in a volume chain, then the storage path is explicitly defined, but the virtual machine becomes unavailable when host changes or storage paths are modified
Solution Approach 1:
The patent changes the reference parameter from absolute paths to relative paths. When a volume is unlinked from a volume chain, the system updates the storage reference from an absolute path (e.g., /host/storage/volume.img) to a relative path (e.g., ../parent-volume/volume.img), allowing the VM to maintain volume chain integrity across different hosts and storage configurations
Solution Approach 2:
The patent implements dynamic reference updating where relative paths are generated and maintained based on the volume chain structure. When volumes are added or removed from the chain, the system dynamically adjusts the relative references of affected volumes to maintain correct paths, enabling adaptability to structural changes
2Adaptability or versatility
If relative references are used for volumes in a volume chain, then the virtual machine can operate across different hosts, but maintaining correct relative paths becomes complex when volumes are added or removed
Solution Approach 1:
The patent implements a feedback mechanism where the system automatically detects changes in the volume chain structure (additions or removals) and triggers reference updates. When a volume is unlinked, the system feedbacks to update the relative paths of child volumes, automatically maintaining correctness without manual intervention
Solution Approach 2:
The patent introduces a volume chain management intermediary that handles reference path calculations and updates. This intermediary component manages the complexity of maintaining relative paths by automatically computing correct relative references based on the current volume chain structure, isolating the complexity from the main VM operation logic
3Loss of substance
If a volume is removed from a volume chain, then storage resources are freed, but child volumes lose their reference to the storage
Solution Approach 1:
The patent performs preliminary action by proactively updating the relative references of child volumes before or during the volume removal process. When a volume is unlinked from the chain, the system automatically updates the storage reference paths of all child volumes to point to their new parent volume, ensuring reference integrity is maintained while allowing storage resource release
Data Source
AI summary
A request to delete a snapshot of a virtual machine may be received. The snapshot may be in a volume chain that may include a first storage volume, a second storage volume associated with the snapshot, and a third storage volume. The first storage volume may include a first storage reference. The second storage volume may include a second storage reference. The third storage volume may include a third storage reference relative to the second storage reference. The second storage volume may be merged with the first storage volume preceding the second storage volume in the volume chain. The third storage reference may be updated to be relative to the first storage reference in view of the second storage reference. The snapshot and the second storage volume may be deleted.