Virtual Machine Migration Triangle Approach
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Solution Overview
Problem
The migration of virtual machine instances across host computer systems is often time-consuming and disrupts user interaction, especially when dealing with large or complex systems, and can result in operational issues due to volatile system resources like attached storage and network connections.
Innovation Solution
The implementation of a method that manages virtual machine instance migration by using a triangle approach to handle input-output requests, ensuring correct ordering and state preservation through phased migration and lease management of block storage devices, allowing for seamless transition between source and target host systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the virtual computer system is halted to copy memory and system state during migration, then the migration process can be completed, but the user interaction capability is eliminated or severely restricted and the migration time becomes significant
Solution Approach 1:
The patent applies preliminary action by starting the virtual computer system on the destination host before completing the memory and system state copy. This allows the system to be partially operational during migration, enabling user interaction while the migration process continues in the background.
Solution Approach 2:
The patent implements continuity of useful action by allowing the virtual computer system to remain operational and accept user interactions during the migration process. The system continues to function on the destination host while memory and system state are being copied, eliminating downtime and maintaining continuous service availability.
2Reliability
If the virtual computer system is halted during migration, then the memory and system state can be copied, but the ability of users to interact with the system is eliminated or severely restricted
Solution Approach 1:
The system is started on the destination host before the memory and system state copy is complete. This preliminary action enables users to interact with the system immediately while the copy process continues, maintaining ease of operation without compromising state copy accuracy.
Solution Approach 2:
The virtual computer system maintains continuous operational capability during migration. Users can interact with the system on the destination host throughout the migration process, ensuring ease of operation is not degraded while the state copy proceeds in the background.
3Ease of operation
If system resources like attached storage and network connections are accessed during migration, then the system remains operational, but the migrated system may differ significantly from the original due to resource volatility
Solution Approach 1:
The patent uses an intermediary approach by having the virtual computer system on the destination host act as a mediator during migration. The system can access stable resources while the memory and system state are being copied, allowing operational continuity while minimizing the impact of volatile resource changes through careful resource management and synchronization.
Data Source
AI summary
Techniques for preserving the state of virtual machine instances during a migration from a source location to a target location are described herein. A set of credentials configured to provide access to a storage device by a virtual machine instance at the source location is provided to the virtual machine instance. When the migration from the source location to the target location starts, a second set of credentials configured to provide access to a storage device by a virtual machine instance at the source location is provided to the virtual machine instance. During the migration, a response to an input-output request is provided to one or more of the locations using the set of credentials and based at least in part on the state of the migration.