Storage Volume Migration via Virtual Identifier Mediation
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Solution Overview
Problem
Existing storage systems face challenges in minimizing downtime during volume migration between storage subsystems, particularly when identifiers like volume numbers change, leading to extensive data changes and increased downtime in large-scale computer systems.
Innovation Solution
A method for migrating volume pairs between storage subsystems while maintaining non-stop operation by creating virtual logical volumes with identical identifiers, allowing seamless access and data replication without altering host settings, and enabling synchronous remote copying without additional functions on the migration-source storage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If volume migration is performed using conventional methods, then data can be migrated from source to destination storage subsystem, but host I/O must be stopped and extensive data changes occur leading to increased downtime
Solution Approach 1:
The patent introduces a migration destination storage subsystem as an intermediary that receives volume data without requiring changes to host settings. The destination subsystem assumes the volume identifier and responds to host I/O requests, allowing migration to proceed while hosts continue operating. This mediator approach enables seamless transition from source to destination without host involvement or downtime.
Solution Approach 2:
The patent performs preliminary data copying from the source storage subsystem to the destination storage subsystem before completing the migration switch. The destination subsystem预先 receives and stores volume data, then assumes the volume identifier, enabling the host to continue I/O operations throughout the process without interruption or downtime.
2Adaptability or versatility
If volume migration is performed with identifier changes, then data can be migrated to new storage subsystem, but extensive data changes occur requiring host setting modifications
Solution Approach 1:
The migration destination storage subsystem acts as an intermediary that assumes the volume identifier, eliminating the need for host setting changes. When the destination subsystem receives the volume, it takes over the identifier and responds to host I/O requests directly, making the migration transparent to hosts and avoiding complex configuration modifications.
Solution Approach 2:
The patent changes the parameter ownership by having the destination storage subsystem assume the volume identifier rather than changing the identifier itself. This parameter transfer approach allows storage subsystem replacement while maintaining the same identifier, thus avoiding the need to modify host settings or configuration data.
3Adaptability or versatility
If migration-source storage system must provide migration function, then PVOL can be migrated, but old-model storage systems cannot migrate volumes
Solution Approach 1:
The patent uses the migration destination storage subsystem as a mediator that performs the actual volume reception and identifier assumption. The source storage subsystem only needs to send data to the destination, which then takes over the volume identifier and handles host I/O requests. This eliminates the requirement for source systems to have migration capabilities, enabling old-model systems to be replaced.
Solution Approach 2:
Instead of requiring the source storage subsystem to perform migration functions, the patent inverts the approach by having the destination storage subsystem perform the migration reception and identifier assumption. The destination system actively receives data and assumes the volume identity, while the source system passively provides data, enabling cross-generation migration.
Data Source
AI summary
A source remote copy configuration in a source storage system is migrated to a destination storage system as a destination remote copy configuration. The destination primary storage apparatus of the destination storage system defines a virtual volume mapped to the primary volume provided by the source primary storage apparatus which is a storage area of the virtual volume; takes over a first identifier of the primary volume to the virtual volume; transfers, when the virtual volume receives an access request, the access request to the source primary storage apparatus to write data in the primary volume; and takes over the first identifier from the virtual volume to another primary volume provided by the destination primary storage apparatus, after completion of copy of data from primary volume of the source primary storage apparatus into primary volume of the destination primary storage apparatus and secondary volume of the destination secondary storage apparatus.