NAS Server Migration Using Volume Conversion and Mirrored Cutover
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Solution Overview
Problem
Conventional NAS server migration across storage arrays is hindered by the need to generate mappings, which can take several minutes, leading to prolonged data unavailability and potential data loss due to the inability of NAS clients to access tunnel volumes during the migration process.
Innovation Solution
Convert tunnel volumes on a source array to normal volumes, migrate the NAS server to a destination array, mirror the normal volumes, and then switch to accessing corresponding volumes on the destination array, all while maintaining transparency to NAS clients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tunnel volumes are accessed through tunnel endpoints during NAS server migration, then data accessibility is maintained, but mapping generation takes several minutes causing data unavailability
Solution Approach 1:
The patent converts tunnel volumes to normal volumes before migrating the NAS server. This preliminary conversion eliminates the need for time-consuming mapping generation after migration, as normal volumes can be accessed directly without tunnel endpoint abstractions. The conversion is performed in advance while the NAS server is still operational on the source array.
Solution Approach 2:
The patent introduces a restricted host as an intermediary component that facilitates access to normal volumes during the migration process. This restricted host acts as a mediator between the NAS server and the storage volumes, enabling the NAS server to access volumes on the destination array before the migration is complete, thereby avoiding data unavailability.
2Productivity
If NAS server is stopped on source array and started on destination array, then migration is completed, but tunnel volumes become inaccessible during the transition
Solution Approach 1:
The patent ensures continuous volume accessibility during migration by converting tunnel volumes to normal volumes and using a restricted host to maintain access paths. The NAS server can continue to access volumes throughout the migration process without interruption, as the normal volumes and restricted host provide uninterrupted access paths even when the NAS server is stopped on the source array and started on the destination array.
3Loss of time
If tunnel volumes are converted to normal volumes, then migration time is reduced, but device configuration complexity increases
Solution Approach 1:
The patent discards the tunnel endpoint abstraction layer by converting tunnel volumes to normal volumes. This eliminates the complex mapping relationships between tunnel endpoints and volumes. The restricted host is introduced as a temporary configuration that simplifies access to normal volumes during migration, and can be discarded or recovered as needed during the migration process.
Data Source
AI summary
Techniques are directed to performing NAS server migration (e.g., between arrays or appliances). Such a technique involves, after a NAS server has accessed source volumes on a source array through a tunnel endpoint on the source array, configuring the NAS server to access the source volumes through source devices of the source array in place of the tunnel endpoint on the source array. Such a technique further involves, after the NAS server is configured to access the source volumes through the source devices of the source array, moving the NAS server from the source array to a destination array. Such a technique further involves, after the NAS server is moved from the source array to the destination array, configuring the NAS server to access destination volumes on the destination array in place of the source volumes on the source array.