Live Migration for Virtual Computing Resources Using Network-Based Storage
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Solution Overview
Problem
Virtualized computing resources face challenges in maintaining data integrity and performance during live migration across network-based storage, as modifications may not be confirmed before instance migration, potentially leading to data inconsistencies and service disruptions.
Innovation Solution
Implementing a live migration process with phases such as prepare, flip, and cleanup, where the control plane prepares the destination host, pauses the instance, copies data, modifies access limitations, and ensures data consistency through network-based storage access control mechanisms, allowing minimal downtime and maintaining data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If live migration is performed without storage access control mechanisms, then migration speed is improved, but data consistency deteriorates
Solution Approach 1:
The system establishes storage access control mechanisms before the live migration begins. The destination host is pre-configured with proper storage access permissions, and the storage system is prepared to handle the migration. This preliminary setup ensures that when data blocks are transferred during migration, the storage system can properly manage access rights and data integrity, preventing consistency issues while maintaining migration speed.
Solution Approach 2:
The storage system acts as an intermediary between the source and destination hosts during live migration. It manages the data transfer process, handling access control requests and ensuring data consistency. The storage system mediates the migration by coordinating data block transfers, updating access rights, and maintaining integrity without requiring the migration process to slow down for consistency checks.
2Reliability
If storage access control mechanisms are implemented during live migration, then data consistency is improved, but operational complexity worsens
Solution Approach 1:
The storage system implements self-service mechanisms for managing access control during live migration. It automatically detects migration events, updates access rights for data blocks, and manages the transition of ownership from source to destination host without external intervention. This automation maintains data consistency while minimizing the operational complexity burden on users.
Solution Approach 2:
The system employs feedback mechanisms where the storage system continuously monitors the migration process and adjusts access control permissions in real-time. As data blocks are transferred and confirmed at the destination, the storage system receives feedback and updates access rights accordingly. This automated feedback loop ensures data consistency without requiring complex manual coordination.
3Manufacturing precision
If instance operation is paused during data copying, then data integrity is improved, but service availability deteriorates
Solution Approach 1:
The system performs preliminary actions by establishing storage access control and preparing the destination host before pausing the instance. Data blocks are identified and access rights are pre-configured. This preparation allows the actual data copying to proceed with minimal or no instance pause, as the storage system can manage the transfer without requiring the instance to be fully stopped, thereby maintaining both data integrity and service availability.
Solution Approach 2:
The live migration process uses periodic actions by pausing the instance only for brief intervals during critical data transfer phases, rather than maintaining a continuous pause. The instance operates normally during non-critical phases while data is being transferred. This periodic pausing strategy ensures data integrity during critical moments while maximizing service availability overall.
Data Source
AI summary
Live migration may be performed for virtual computing resources utilizing network-based storage. A virtual compute instance operating at a source host may be moved to a destination host. The virtual compute instance may be a client of a network-based storage resource that stores data for the virtual compute instance. Access to the data stored for the virtual compute instance may be limited to the source host. When migration is performed, the destination host may be prepared to assume operation of the virtual compute instance. Operation of the virtual compute instance at the source host may be paused and the access to the data at the network-based storage resource may be modified to limit access to the destination host. Operation of the virtual compute instance may then resume at the destination host.