Non-disruptive Data Migration Between Non-shared Storage Hosts
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Solution Overview
Problem
Data migration between storage servers that do not share storage, such as those using direct-attached storage (DAS), is typically disruptive to client applications, causing apparent downtime.
Innovation Solution
The technique employs RAID-level mirroring with a sub-RAID level proxy to mirror aggregates from non-shared storage, allowing relocation without direct shared storage connectivity, using proxy components to facilitate data communication and relocation between hosts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data migration is performed between storage servers that do not share storage (DAS environment), then data relocation is achieved, but client applications experience downtime and disruption
Solution Approach 1:
The patent performs preliminary actions by creating a mirror aggregate on the destination storage server before actually migrating data. The mirror aggregate is prepared in advance with the same structure and capacity, allowing the migration to proceed without disrupting client applications. The mirror is created using existing storage resources before the migration begins, ensuring that the destination is ready to immediately assume the workload.
Solution Approach 2:
The patent introduces an intermediary mechanism by using a mirror aggregate as a buffer between source and destination storage servers. This mirror aggregate acts as a mediator that receives data from the source while clients continue to access data from the original location, enabling seamless migration without direct client involvement or service interruption.
2Adaptability or versatility
If RAID-level mirroring is used to mirror aggregates from non-shared storage, then direct shared storage connectivity is not required, but additional proxy components and complexity are introduced
Solution Approach 1:
The patent applies universality by designing the proxy components to perform multiple functions: they manage the mirror aggregate creation, handle data synchronization between source and destination, and coordinate the migration process. This multi-functional approach reduces the need for separate specialized components for each migration task, thereby managing complexity while achieving versatile migration capability between non-shared storage systems.
3Adaptability or versatility
If aggregate relocation is performed without direct shared storage connectivity, then migration flexibility is improved, but data synchronization between source and destination becomes more complex
Solution Approach 1:
The proxy components serve as intermediaries that manage data synchronization between source and destination storage servers without requiring direct shared storage connectivity. The proxy on the destination server receives data from the source server and maintains synchronization, abstracting the complexity of distributed data coordination from the overall migration system.
Data Source
AI summary
A technique is disclosed for non-disruptive migration of data between storage on hosts that do not share storage with each other. Aggregate relocation is enabled to operate between the hosts in the absence of shared storage connectivity. The technique includes mirroring an aggregate from storage of a first host to storage of a second host by using a sub-RAID level proxy in each of the first and second hosts to proxy data communications between the hosts. The proxy is used in lieu of the mirroring application in the first host having direct access to the storage devices of the second host. The technique further includes relocating the aggregate from the first host to the second host.