Dual-Controller Storage Locking via Shared Communication Areas
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Solution Overview
Problem
Existing RAID-based storage systems face challenges in providing a secure and reliable locking mechanism to prevent conflicts between concurrent operations by two storage control nodes accessing the same storage area, without requiring additional hardware or software configurations.
Innovation Solution
A method and system that utilize shared communication areas with different access permissions for two controllers to manage lock flags, allowing one controller to lock a storage area only if it is not already locked by the other controller, without the need for an extra communication channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two storage control nodes operate in parallel to process data access operations, then system productivity and performance are improved, but conflicts between concurrent operations on the same storage area occur
Solution Approach 1:
The patent introduces communication areas as intermediary structures between the two storage control nodes. These communication areas store lock flags that mediate the coordination between nodes, allowing them to detect and prevent conflicts without direct interference. The intermediary mechanism enables parallel operation while maintaining operational consistency through shared state information.
2Reliability
If a locking mechanism is implemented to prevent conflicts between controllers, then operation reliability is improved, but system complexity increases
Solution Approach 1:
The locking mechanism is segmented into independent communication areas, each associated with specific storage areas. Rather than implementing a single complex global lock, the system divides the locking functionality into multiple simple, independent units. Each communication area maintains its own lock flag, allowing fine-grained control without the overhead of a monolithic locking system.
Solution Approach 2:
The patent uses lock flags as simplified copies or representations of the actual storage area lock state. Instead of implementing complex inter-controller communication protocols or hardware arbitration, the system uses simple binary flag copies in communication areas to represent whether a storage area is locked. This copying approach dramatically reduces mechanism complexity while maintaining reliability.
3Reliability
If additional hardware devices are added to provide locking functionality, then locking reliability is improved, but device complexity and cost increase
Solution Approach 1:
The communication areas serve multiple functions: they store lock flags for conflict prevention, and they can be used for other inter-controller communication needs. By making the communication infrastructure multi-functional, the patent eliminates the need for dedicated hardware locking devices. The existing communication pathways are repurposed to provide locking functionality, reducing overall system complexity while maintaining reliability.
Data Source
AI summary
A method and a system for locking a storage area in a storage system. There is provided a method for locking a storage system in a storage system, where the storage system comprises a first controller, a second controller, a first communication area and a second communication area. The method comprises: a first lock flag associated with the storage area is written to the first communication area in response to receiving at the first controller a data access request with respect to the storage area, where the first communication area being readable and writable to the first controller and being readable to the second controller. A second lock flag associated with the storage area is read from the second communication area, where the second communication area being readable to the first controller and being readable and writable to the second controller. The storage area is locked by the first controller in response to the second lock flag indicating that the storage area is not locked by the second controller.