Persistent Fence for Synchronous Replication Sync State
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Solution Overview
Problem
Existing data storage systems face challenges in maintaining multiple synchronized copies of data transactions to meet redundancy requirements, as failures can lead to divergence between primary and replicated storage objects, violating data storage redundancy specifications.
Innovation Solution
The implementation of synchronous replication with file system dependent and independent techniques, utilizing a persistent fence to selectively allow or block operations based on the synchronization state of the replication relationship, ensuring that operations are only executed if successfully replicated to both storage objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous replication is implemented to maintain multiple copies of data, then data storage redundancy is improved, but system complexity increases due to the need to manage replication relationships and fencing mechanisms
Solution Approach 1:
The patent introduces a fence mechanism as an intermediary component that mediates between the primary storage object and secondary storage objects. The fence acts as a coordinator that manages replication relationships, tracks synchronization states, and controls operation blocking/unblocking, thereby simplifying the overall system architecture while maintaining data redundancy
Solution Approach 2:
The system implements feedback mechanisms through the fence that continuously monitors the replication relationship between primary and secondary storage objects. When the replication relationship is broken or out of sync, the fence receives feedback and automatically blocks operations to prevent data divergence, ensuring redundancy is maintained without requiring complex manual management
2Reliability
If operations are blocked when replication relationship is out of sync, then data integrity is improved, but productivity decreases due to operation blocking
Solution Approach 1:
The fence mechanism dynamically adjusts its behavior based on the replication relationship state. When the replication relationship is healthy and in sync, the fence allows operations to proceed normally, maintaining high productivity. When the replication relationship breaks or becomes out of sync, the fence automatically blocks operations to prevent data divergence, ensuring data integrity. This dynamic adaptation resolves the contradiction between productivity and data integrity
3Productivity
If the fence is deactivated to allow operations, then productivity is improved, but the risk of data divergence increases when replication is out of sync
Solution Approach 1:
The fence continuously receives feedback about the replication relationship state from the storage system. Based on this feedback, the fence intelligently decides when to activate (block operations) and when to deactivate (allow operations). This feedback-driven control ensures that operations are only allowed when replication is synchronized, preventing data divergence while maintaining productivity when conditions permit
Data Source
AI summary
Techniques are provided for synchronous replication for synchronous mirror copy guarantee. A file system dependent technique for synchronous mirror copy guarantee is provided by overriding default behavior of a persistent fence so that the persistent fence is activated to block operations targeting a storage object having a synchronous replication relationship based upon the synchronous replication relationship being out of sync. The default behavior of the persistent fence is overridden to allow operations to be executed upon the storage object based upon the synchronous replication relationship being in sync. A file system independent technique for synchronous mirror copy guarantee is provided by intercepting operations before the operations are received by a file system. The operations are selectively forwarded to the file system or not based upon a state of a synchronous replication relationship.