Distributed Storage Controller Replication Transition
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Solution Overview
Problem
Conventional data replication methods face challenges during transitions from asynchronous to synchronous modes, leading to potential race conditions that can result in inconsistent target replica consistency and inefficiencies in information processing systems.
Innovation Solution
The implementation of a distributed storage controller with a clustered content addressable storage system that ensures consistent initiation of data replication across multiple processing modules, including restarting the asynchronous-to-synchronous transition cycle scan operation when necessary, to maintain target replica consistency and improve replication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous replication mode is initiated during asynchronous replication, then data consistency is improved, but race conditions may occur leading to replication failures
Solution Approach 1:
The system performs a preliminary cycle scan operation before initiating synchronous replication mode to identify and replicate any pending data changes. This preliminary action ensures that all data modifications are captured before the replication mode transition, preventing race conditions where writes might be lost during the transition from asynchronous to synchronous mode.
2Reliability
If asynchronous-to-synchronous transition cycle scan operation is restarted, then replication consistency is improved, but system performance may be impacted
Solution Approach 1:
The system implements periodic cycle scan operations that can be restarted when needed during the transition from asynchronous to synchronous replication mode. These periodic scans are performed at controlled intervals and only when necessary to maintain consistency, rather than continuously, thus balancing replication reliability with system performance by minimizing the frequency and duration of scan operations.
Data Source
AI summary
A first storage system in one illustrative embodiment is configured to participate in a replication process with a second storage system. In conjunction with a synchronous replication mode of the replication process, a first processing module of a distributed storage controller of the first storage system is configured to write one or more data pages in the first storage system in accordance with a write request received from a host device, to send a corresponding replication write request to the second storage system, to determine whether or not the one or more data pages have been successfully replicated to the second storage system, and to update content-based signature mapping information of the one or more data pages responsive to receipt of an indication of successful replication. Responsive to a determination that the write request was received prior to initiation of the synchronous replication mode, an asynchronous-to-synchronous transition cycle scan operation is restarted.