Storage Controller Path Switching for Host-Continuous Replacement
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Solution Overview
Problem
Existing storage controller replacement methods require stopping the host system to avoid data loss during the transition, which is inefficient and disruptive.
Innovation Solution
A storage controller system with a switch unit and dual storage control devices that manage IO routing and address conversion, allowing seamless transition without host interruption by using port and route management tables to redirect IO paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage controller is replaced by stopping the host system, then data loss during transition is prevented, but system availability and productivity are reduced
Solution Approach 1:
The patent applies preliminary action by pre-configuring dual storage controllers and establishing IO path redundancy before replacement is needed. The system maintains ready-to-use alternative controllers with pre-established connection paths, so when replacement is required, the switch can occur immediately without stopping the host, thus preventing both data loss and downtime.
Solution Approach 2:
The switch unit acts as an intermediary between the host and storage controllers. It manages multiple IO paths and can redirect traffic from one controller to another without involving the host system. This intermediary mechanism enables seamless controller replacement by absorbing the transition and presenting continuous service to the host.
2Ease of manufacture
If the connection path is switched during storage controller replacement, then replacement can proceed, but disconnection may occur causing data loss
Solution Approach 1:
The system performs preliminary configuration of alternative IO paths and validates the standby controller before actual replacement occurs. The switch unit pre-establishes routing tables and connection parameters for both active and standby controllers, ensuring that when the switch occurs, the alternative path is already optimized and ready, preventing disconnection issues.
Solution Approach 2:
The patent implements beforehand cushioning by maintaining redundant IO paths and buffer mechanisms that can absorb connection transitions. The switch unit keeps alternative routes ready and can temporarily route through backup paths during the transition, cushioning against any disconnection events that might occur during controller replacement.
3Productivity
If redundant connection paths are configured for both storage controllers, then seamless replacement is enabled, but device complexity increases
Solution Approach 1:
The switch unit is designed with universal functionality to handle multiple storage controllers and various IO path configurations through a single unified interface. It can manage redundant connections, perform address translation, and route IO operations regardless of which controller is active, simplifying the overall system architecture despite the presence of multiple controllers.
Solution Approach 2:
The system uses address translation and path copying mechanisms where the switch unit maintains copies of controller addresses and path information. When switching controllers, it translates addresses from the old controller to the new one using pre-stored mapping information, avoiding the need for complex reconfiguration and reducing the apparent complexity for the host system.
Data Source
AI summary
To replace a storage controller without stopping a host and without losing data related to IO processing from the host. A storage controller sets, in a port management table, a first host path definition between the host and first address information in a controller unit in addition to a second host path definition between the host and second address information in a controller unit. The storage controller sets, in a route management table, a first connection route between an input port and a first output port to which a port of the first address information is connected, in addition to a second connection route between an input port and a second output port to which a port of the second address information is connected. The storage controller transfers an IO to one controller unit or another controller unit based on the port management table and the route management table.