Virtual Machine Disk State Inheritance Hierarchy Depth
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Solution Overview
Problem
Conventional disk state inheritance in virtual machine forking increases the depth of the disk hierarchy, leading to significant performance degradation in disk I/O operations, making repeated use of VM forking impractical and causing unacceptable performance issues in scenarios like virtual desktop infrastructure deployments.
Innovation Solution
The techniques involve taking a snapshot of the parent VM's current running point to create a delta disk for the child VM, copying the content of the parent disk to the child disk, and re-parenting the child disk to directly point to a base disk, thereby maintaining the same hierarchy level as the parent disk, preventing an increase in hierarchy depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional disk state inheritance is used in VM forking, then child VMs can inherit parent VM's disk state, but the depth of the disk hierarchy increases causing performance degradation
Solution Approach 1:
The patent changes the dimensional structure of the disk hierarchy by allowing child disks to point directly to the base disk (skipping intermediate parent disks), effectively collapsing the hierarchical depth while maintaining the inheritance relationship. This dimensional restructuring resolves the performance degradation caused by deep hierarchies.
Solution Approach 2:
The patent extracts the intermediate parent disk from the inheritance path between child disk and base disk. By having child disks point directly to the base disk rather than through multiple parent disks, the harmful intermediate layers are removed, eliminating the performance penalty of deep hierarchy traversal.
2Adaptability or versatility
If VM forking is repeated multiple times, then more child VMs can be created, but performance degradation accumulates making repeated forking impractical
Solution Approach 1:
The patent enables repeated VM forking by restructuring the disk hierarchy dimensionally, allowing multiple child disks to point directly to the same base disk without creating intermediate hierarchy levels. This allows unlimited forking operations without cumulative performance degradation.
3Reliability
If child disk points to parent disk in hierarchy, then disk state inheritance is achieved, but hierarchy depth increases causing performance issues
Solution Approach 1:
The patent extracts intermediate parent disks from the inheritance path, creating a direct pointer relationship between child disks and the base disk. This removes the complexity of deep hierarchy traversal while preserving the disk state inheritance functionality.
Data Source
AI summary
Techniques for handling inheritance of disk state when forking virtual machines (VMs) are provided. In one embodiment, a computer system can receive a request to fork a child VM from a parent VM. In response, the computer system can take a disk snapshot of the parent VM, where the disk snapshot results in a child disk for the child VM, where the child disk is a delta disk that points to a parent disk of the parent VM, and where the parent disk serves as the parent VM's current running point. The computer system can then determine whether the parent disk is a delta disk. If so, the computer system can copy the content of the parent disk to the child disk, traverse a disk hierarchy associated with the parent disk to identify a base disk above the parent disk in the hierarchy, and cause the child disk to point directly to the base disk.