Storage Device Controller Cache Data Duplication Management
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Solution Overview
Problem
Current storage devices face limitations in managing cache data duplication and selecting cache memory, particularly when a failure occurs in the storage device management unit, as the method for duplicating and holding cache data is inflexible and lacks freedom in selecting cache memory for redundancy.
Innovation Solution
A storage device with multiple controllers, each equipped with cache memory, manages cache data duplication by using predetermined management information to select a new paired destination controller in case of failure, and forwards cache data to ensure continuous availability and flexibility in cache memory selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a storage device management unit determines the disk controller for duplicating cache data, then the cache data duplication can be managed, but if a failure occurs in the storage device management unit, the disk controller for duplicating and holding the cache data cannot be changed
Solution Approach 1:
The patent divides the cache data duplication management function from the centralized storage device management unit and distributes it to each disk controller. Each controller now independently manages its own cache data duplication by selecting paired destination controllers, eliminating the single point of failure and enabling flexible reconfiguration when failures occur.
Solution Approach 2:
Each disk controller is empowered to autonomously determine and manage its own cache data duplication by selecting paired destination controllers from available controllers. This self-service approach allows controllers to adapt to failures without requiring intervention from a central management unit, improving both reliability and flexibility.
2Reliability
If multiple disk controllers hold cache data with duplication, then the availability of cache data is improved, but the method for selecting cache memory for duplication has low degree of freedom
Solution Approach 1:
The patent implements a dynamic selection mechanism where each disk controller can choose from multiple available controllers as paired destinations for cache data duplication. The selection is not fixed but can be dynamically adjusted based on controller availability and system state, providing both high availability and selection freedom.
Solution Approach 2:
The system allows changes in the configuration parameters of cache data duplication by enabling controllers to select different paired destination controllers based on varying system conditions. This parameter flexibility maintains reliability while providing degree of freedom in cache memory selection.
Data Source
AI summary
In a storage device according to the present invention, controllers each having a cache memory manage duplication of cache data. A storage device SD includes multiple controllers 1 each including a cache memory, and multiple storing units 21 used by the controllers and configured with logical volume 24 for being provided to a higher-level device 3. Each of the controllers, in a case where a paired destination controller forming a duplication pair is blocked, selects a new paired destination controller for each logical volume, forwards the cache data stored in the cache memory included in the own controller to the new paired destination controller, and stores the cache data in a cache memory included in the new paired destination controller to duplicate the cache data.