Triangular Asynchronous Replication for Storage Latency
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Solution Overview
Problem
Current data replication systems, such as synchronous and semi-synchronous RDF systems, face latency issues and data consistency problems, especially over long distances, and existing solutions like SAR processes require significant overhead and may result in data loss during failures.
Innovation Solution
A system that provides chunks of data to a remote destination with indicators for storage, maintains maps for data synchronization, and determines the most up-to-date data between local and remote destinations to ensure consistency and reduce latency by copying data from the most updated source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous RDF transfer is used to ensure data consistency between primary and secondary storage devices, then data reliability is improved, but write operation latency increases due to waiting for acknowledgment
Solution Approach 1:
The patent segments the acknowledgment process by introducing sequence numbers and dividing data into chunks. The primary storage device can acknowledge writes to the host using sequence numbers without waiting for full transfer completion to the secondary device, while still maintaining data consistency through structured data division and tracking.
Solution Approach 2:
The patent implements preliminary action by pre-allocating sequence numbers and preparing data chunks before actual transfer. The primary storage device can acknowledge writes to hosts based on pre-assigned sequence numbers, allowing the transfer to the secondary device to proceed in the background without blocking the host operation.
2Speed
If semi-synchronous RDF transfer is used to reduce latency by acknowledging writes immediately, then write operation speed is improved, but data consistency is compromised because previous transfers must be acknowledged first
Solution Approach 1:
The patent implements feedback mechanisms through sequence numbers and acknowledgment tracking. The system provides structured feedback about which data chunks have been successfully transferred and acknowledged, allowing the primary device to maintain consistency information without being blocked by previous transfer completions.
Solution Approach 2:
The patent enables continuous data transfer operations by allowing multiple transfer iterations to proceed overlapping. While one data chunk is being transferred to the secondary device, the primary device can already acknowledge subsequent writes to hosts, maintaining continuous operational flow without sequential bottlenecks.
3Speed
If asynchronous background copy is used to eliminate latency, then write operation speed is improved, but data consistency cannot be guaranteed between primary and secondary storage devices
Solution Approach 1:
The patent implements comprehensive feedback through sequence numbers, chunk tracking, and acknowledgment mechanisms. Even in asynchronous operation, the system continuously monitors transfer status and maintains consistency information, allowing the host to receive immediate acknowledgment while the system tracks and ensures eventual data consistency between primary and secondary devices.
Data Source
AI summary
Storing recovery data includes providing chunks of data to a remote destination, where each chunk of data represents data written before a first time and after a second time and where the second time for one of the particular chunks corresponds to a first time for a subsequent one of the particular chunks, providing synchronous data to a local destination, and providing an indicator to the local destination in connection with creation of a new chunk of data for storage at the remote destination. The local destination may maintain a plurality of maps, where each of the maps associates synchronous data being provided thereto with a specific chunk of data. In response to receiving an indicator in connection with creation of a new chunk of data, the local destination may point to a new map. There may be two maps or more than two maps.