Extent Command Ordering in Data Replication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional data replication methods, such as synchronous Remote Data Facility (RDF) systems, face increased latency due to the need for acknowledgement of write operations across long distances, which can be unacceptable in disaster recovery scenarios.
Innovation Solution
A method that orders data IO captured at a primary site for application at a secondary site by removing extent-level portions, determining if they need to overwrite data, and applying them before the captured data IO, using commands like UNMAP and XCOPY to ensure time-sequenced and consistent replication.
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 integrity is maintained, but latency increases due to waiting for acknowledgement across long distances
Solution Approach 1:
The patent applies preliminary action by sending the write acknowledge to the host before the RDF transfer to the secondary storage device is completed. This allows the host to proceed with operations immediately without waiting for the remote transfer to finish, thereby reducing latency while maintaining data consistency through subsequent acknowledgment mechanisms.
Solution Approach 2:
The patent introduces an intermediary acknowledge message that decouples the host's write operation from the completion of the remote RDF transfer. This intermediary mechanism allows the host to receive confirmation of its write operation immediately, while the actual data replication continues in the background, thus resolving the latency issue without compromising data integrity.
2Reliability
If extent-level commands are included in data IO replication, then comprehensive data consistency is achieved, but processing complexity increases
Solution Approach 1:
The patent segments the data IO processing by separating extent-level commands from regular data writes. This segmentation allows the system to handle different types of operations independently, applying appropriate processing logic to each type, thereby reducing overall processing complexity while maintaining comprehensive data consistency.
Solution Approach 2:
The patent applies partial action by selectively processing extent-level commands only when necessary, rather than treating all data IO operations uniformly. This approach reduces processing complexity by avoiding unnecessary processing steps for operations that don't require extent-level handling, while still ensuring data consistency when needed.
Data Source
AI summary
A method, system, and computer program product for ordering a plurality of data IO captured at a primary site to be applied at a secondary site, comprising removing the one or more extent level portions from the captured data IO, determining if the one or more extent level portions are time sequenced to overwrite a portion of data of the data IO, based on a determination that the portion data is to be overwritten, removing the overwritten portion of data from the plurality of the data IO and ordering the one or more extent level portions to be applied at the secondary site before the captured data IO.