Virtual Disk Live Migration via Snapshot Mirroring
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Solution Overview
Problem
Existing virtual machine migration technologies require shutdown and result in data inconsistencies or losses during storage device changes, limiting administrative tasks and performance enhancements.
Innovation Solution
The system performs live migration of a virtual disk by creating a snapshot, mirroring changes, and transferring the snapshot between storage devices while the virtual machine is executing, ensuring data consistency and minimizing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If virtual machine migration is performed using existing technologies, then the virtual machine can be moved between physical machines, but the virtual machine must be shut down resulting in data inconsistencies or losses during storage device changes
Solution Approach 1:
The patent applies preliminary action by creating a snapshot of the virtual disk before migration begins. This snapshot captures the state of the virtual disk at a specific point in time, allowing the migration process to proceed while maintaining data consistency. The snapshot is then mirrored to the target storage device, ensuring that no data is lost or corrupted during the migration process, even while the virtual machine remains operational.
Solution Approach 2:
The patent uses copying by creating and mirroring a snapshot of the virtual disk to the target storage device. Instead of directly migrating the live virtual disk, a copy (snapshot) is created and synchronized to the target device. This copying mechanism ensures data consistency while allowing the virtual machine to continue operating, resolving the contradiction between reliability and operational continuity.
2Productivity
If the virtual machine is shut down for storage device changes, then data consistency can be maintained, but administrative tasks and performance enhancements are limited due to downtime
Solution Approach 1:
The patent applies continuity of useful action by enabling the virtual machine to remain operational throughout the migration process. The snapshot and mirroring operations occur in the background without interrupting the virtual machine's execution. This allows administrative tasks such as storage upgrades and load balancing to be performed efficiently without incurring downtime, directly addressing the contradiction between productivity and time loss.
3Speed
If live migration is performed without snapshots, then migration speed is faster, but data inconsistencies occur during the migration process
Solution Approach 1:
The patent applies preliminary action by creating a snapshot before migration begins. This snapshot serves as a baseline that ensures data consistency while the migration proceeds. The snapshot is then mirrored to the target device, maintaining reliability without significantly impacting migration speed, as the snapshot creation is a one-time operation followed by efficient mirroring processes.
Data Source
AI summary
Live migration of a virtual disk of a virtual machine between storage devices is described. In accordance with one example, a computer system prepares a first area of a first storage device and a second area of a second storage device for a live snapshot of a virtual disk of a virtual machine. A transaction is then executed that includes storing the live snapshot in the first area of the first storage device, copying the live snapshot to the second area of the second storage device, and mirroring a change to the virtual disk that occurs after the creation of the live snapshot, where the mirroring is via one or more write operations to the live snapshot in the first area and to the copy of the live snapshot in the second area.