Storage Control Device LUN Conversion for Failover Copy Accuracy
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Solution Overview
Problem
In storage clusters, when a failover occurs during a copy process, the lack of matching logical unit numbers (LUNs) between active and standby storage devices can result in operations being performed on false volumes, leading to errors and increased administrative workload due to the need for identical configurations across both devices.
Innovation Solution
A storage control device that determines whether it is the master device during a copy process and converts identifiers for non-master devices to ensure correct LUNs are used, preventing operations on false volumes by using virtual LUNs that are converted to real LUNs when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LUNs are not matched between active and standby storage devices, then device complexity and administrative workload are reduced, but reliability deteriorates because false volumes may be operated after failover
Solution Approach 1:
The patent introduces a LUN conversion table as an intermediary data structure that maps LUNs from the master device to LUNs on the standby device. During failover, the storage control device consults this conversion table to translate LUN references, ensuring that operations intended for specific volumes are correctly directed even when LUN assignments differ between devices. This mediator approach allows LUNs to remain unmatched between devices while maintaining operational reliability.
2Reliability
If LUNs are matched between active and standby storage devices, then reliability is improved by ensuring correct volume operations after failover, but device complexity increases due to identical configuration requirements
Solution Approach 1:
The patent creates a LUN conversion table that copies and stores the mapping relationships between LUNs on the master device and LUNs on the standby device. Instead of requiring identical LUN configurations, the system copies the necessary mapping information into this table, which is then used during failover to correctly identify volumes. This copying approach maintains reliability without imposing identical configuration requirements.
3Productivity
If failover occurs during copy process with unmatched LUNs, then productivity is maintained by allowing different configurations, but manufacturing precision deteriorates as operations are performed on false volumes
Solution Approach 1:
During copy operations that span failover events, the LUN conversion table serves as an intermediary that ensures copy source and destination identifiers are correctly translated. The storage control device uses this table to maintain accurate mapping between the copy pair volumes even when LUN assignments change during failover, preventing operations on incorrect volumes while maintaining operational continuity.
Data Source
AI summary
A determining unit determines, when a failover occurs, whether the storage device is a master device. If the determining unit determines that the storage device is not the master device, a converting unit converts the virtual LUNs of the copy source and the copy destination to the real LUNs. Then, a copying unit performs a copy process by using the real LUNs converted by the converting unit.