Storage Subsystem Off-Load Data Copy Path Selection
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Solution Overview
Problem
In a storage system providing virtual volumes to host computers, there is a need to select an optimal path for off-load data copy operations when multiple copy sources are available, as existing methods do not efficiently manage data replication and processing loads across storage subsystems.
Innovation Solution
The storage system employs a High Availability (HA) pair configuration where both storage subsystems respond with the same virtual ID, allowing either subsystem to act as the copy source for data replication, thereby optimizing data processing and reducing host computer load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an HA pair configuration is implemented with multiple storage subsystems responding to the same virtual ID, then system reliability is improved, but path selection complexity increases when performing off-load data copy operations
Solution Approach 1:
The storage subsystem automatically determines which volume to use as the copy source by checking whether the copy destination volume exists in its own subsystem or needs to be transferred to another subsystem in the HA pair. This self-service mechanism eliminates the need for complex external path selection logic while maintaining reliability through automatic failover capability.
2Productivity
If off-load data copy is performed from a virtual volume with multiple copy sources, then host computer load is reduced, but data processing time increases due to path selection overhead
Solution Approach 1:
The storage subsystem performs preliminary determination of the copy source volume by checking the existence of the copy destination volume in its own subsystem before initiating the data copy operation. This preliminary action prevents unnecessary path selection delays during the actual data copy process, reducing overall data processing time while maintaining the off-load benefit that reduces host computer load.
3Productivity
If the storage subsystem automatically determines the copy source volume, then path selection efficiency is improved, but control complexity within the storage subsystem increases
Solution Approach 1:
The storage subsystem uses feedback from checking whether the copy destination volume exists in its own subsystem to automatically determine the appropriate copy source volume. This feedback mechanism enables efficient path selection by using simple existence checking logic rather than complex path selection algorithms, improving productivity while minimizing the increase in control complexity to only the necessary volume existence verification step.
Data Source
AI summary
A storage system capable of realizing off-load data copy among storage subsystems constituting an HA pair configuration is provided. Therefore, in an HA pair configuration where a first volume of a first storage subsystem and a second volume of a second storage subsystem respectively respond a same virtual ID to the host, when the first or the second storage subsystem receives an instruction of off-load data copy specifying a virtual ID as the copy destination from the host computer, either a first volume or a second volume is selected as a copy source volume according to a position of a copy destination volume, and data is copied from the selected copy source volume to the copy destination volume.