Hypervisor Logical HBA Migration for Virtual Machines
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Solution Overview
Problem
Current virtual computer migration systems face challenges in live migration of virtual computers between physical machines, particularly in I/O pass-through systems, where simultaneous login to a Fabric using the same WWN from different FC-HBAs is not possible, leading to downtime and incompatibility with Persistent Reservation commands in cluster systems.
Innovation Solution
The system employs a hypervisor to manage key information for access control, allowing seamless migration by switching logical HBA allocations and maintaining access management across physical machines, ensuring continuous operation and compliance with exclusive control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same WWN is used for FC-HBA in both movement source and movement destination, then access path switching is enabled for live migration, but simultaneous login to Fabric from different FC-HBAs is not possible
Solution Approach 1:
The system performs preliminary registration of the movement destination FC-HBA's WWN with the storage device before migration occurs. This advance preparation ensures that when the virtual computer is migrated, the storage device already has the destination WWN registered and can immediately establish the access path without requiring simultaneous login from both source and destination HBAs
Solution Approach 2:
The migration process is segmented into distinct phases: (1) preliminary registration of destination WWN with storage, (2) migration execution, and (3) path switching. This segmentation allows the system to avoid the conflict of simultaneous login by completing registration before the actual migration and path switching occurs
2Reliability
If sequential logout and login is performed for FC-HBA during migration, then access path switching is achieved, but migration time increases by tens of seconds
Solution Approach 1:
The system performs preliminary registration of the movement destination FC-HBA's WWN with the storage device before migration occurs. This advance preparation eliminates the need for time-consuming sequential logout/login operations during migration, as the destination is already registered and ready to accept the access path immediately when migration occurs
Solution Approach 2:
By pre-registering the destination WWN, the system maintains continuous access path availability during migration. The storage device continuously recognizes both the source and destination WWNs, allowing seamless path switching without interruption or time loss associated with logout/login sequences
3Reliability
If Persistent Reservation command is used for exclusive control in cluster systems, then storage access control is ensured, but migration compatibility is reduced due to WWN change restrictions
Solution Approach 1:
The system introduces the movement destination FC-HBA's WWN as an intermediary that is pre-registered with the storage device. This intermediary WWN acts as a bridge that maintains Persistent Reservation compatibility while enabling migration, as the storage device recognizes the pre-registered destination WWN and allows the reservation to transfer seamlessly during migration
Solution Approach 2:
The pre-registration of the destination WWN with the storage device before migration maintains the exclusive control mechanism of Persistent Reservation. By having the destination WWN already registered, the system ensures that when migration occurs, the storage device can maintain the reservation control while switching access from source to destination WWN, thus preserving migration compatibility
Data Source
AI summary
A hypervisor as a movement source stores key information, and the key information is registered in a storage using the stored key information through a logical HBA which is used for migration.