Heterogeneous Storage Volume Online Takeover via Volume Label
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Solution Overview
Problem
Existing methods for online data migration of heterogeneous storage volumes face challenges in multi-path compatibility and require updates to SCSI device numbers, leading to potential conflicts and interruptions in upper layer services during storage volume changes.
Innovation Solution
An online takeover method and system that involves generating and managing volume labels, flushing cache data, changing directory information, and migrating storage volumes between different storage systems without interrupting upper layer services, allowing seamless transition and avoiding conflicts through application layer switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the host switches to an active link for online data migration, then data can be migrated from the original storage system to the new storage system, but the SCSI device number must be updated which causes conflicts and interruptions in upper layer services
Solution Approach 1:
The patent introduces a volume label as an intermediary between the host and storage systems. Instead of directly using SCSI device numbers that cause conflicts, the volume label serves as a stable identifier that the host uses to access storage volumes. This intermediary allows the underlying storage device numbers to change while keeping the host's view consistent, thus enabling data migration without service interruptions
Solution Approach 2:
The patent changes the identification parameter from SCSI device number to volume label. By this parameter substitution, the system can migrate storage volumes between different storage systems without requiring the host to update device identifiers. The volume label remains constant while the physical storage location changes, resolving the conflict between migration and service continuity
2Speed
If the host caches data in memory during upper layer service execution, then data access speed is improved, but data integrity may be compromised during storage volume takeover
Solution Approach 1:
The patent performs preliminary actions in a specific sequence: first the new storage system takes over the storage volume and receives data from the original storage system, then the host flushes its cache data to the new storage system, and finally the host updates its volume label mapping. This preliminary sequencing ensures that all data (including cached data) is safely transferred before the host completes the takeover, maintaining both speed and integrity
Solution Approach 2:
The patent implements a feedback mechanism where the host monitors the takeover process and performs cache flushing based on the state of the storage volume transition. The host receives feedback about the takeover status and adjusts its data access patterns accordingly, flushing cache when necessary and maintaining normal caching operations when the new storage system is fully operational, thus balancing speed and integrity
Data Source
AI summary
An online takeover method for a heterogeneous storage volume, including: executing a service: a host executing upper layer service data access by means of a second volume label of a storage volume of a second storage; generating a volume label: a first storage taking over the storage volume of the second storage and generating a first volume label for the storage volume that has been taken over; flushing data: flushing host side cache data corresponding to the storage volume of the second storage to the storage volume of the second storage; changing a directory: changing directory information of an upper layer service running on the host; and storage migration: when the directory information of the upper layer service has been changed, migrating data of the storage volume to the first storage.