Synchronous Remote Mirroring Data Reduction
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Solution Overview
Problem
Synchronous remote data mirroring faces challenges with increased distance due to inherent delays in transmitting updates and receiving acknowledgments, particularly in scenarios where dedicated data links are costly and bandwidth is intermittently available, leading to potential disruptions during peak loads.
Innovation Solution
Implementing a method where the primary data storage system reduces remote copy data prior to transmission to a secondary storage system, maintaining synchronous mirroring by acknowledging write operations only after the secondary system has received and acknowledged the reduced data, with data reduction techniques like compression and deduplication applied in-band to minimize data transfer while ensuring reversibility for accurate mirroring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous remote data mirroring is implemented over long distances using shared bandwidth networks, then data availability and disaster recovery capability are improved, but transmission delay and acknowledgment time increase due to inherent network latency
Solution Approach 1:
The patent extracts only the essential metadata and change information from the original data blocks, transmitting only these extracted elements to the remote site rather than complete data blocks. This reduces transmission volume and delay while maintaining the ability to reconstruct full data blocks when needed for disaster recovery.
Solution Approach 2:
The system performs preliminary data processing at the primary site by identifying and extracting only the portions of data that have changed since the last synchronization. This preliminary action prepares minimized data sets for transmission, reducing the time required for remote mirroring operations.
2Speed
If dedicated data links are used for synchronous remote mirroring, then transmission speed and reliability are improved, but cost increases significantly
Solution Approach 1:
The patent creates a simplified copy or representation of the data (metadata, change indicators, differential information) that can be transmitted over standard shared networks. This copy contains sufficient information to maintain synchronization without requiring the bandwidth and speed of dedicated links, thereby reducing cost while maintaining functionality.
Solution Approach 2:
The system changes the parameters of data transmission by transforming full data blocks into compressed metadata representations. This parameter change reduces the volume of transmitted data by orders of magnitude, allowing standard shared networks to achieve effective transmission speeds comparable to dedicated links for the purpose of maintaining remote mirrors.
3Reliability
If complete data blocks are transmitted for remote mirroring, then data integrity is ensured, but network bandwidth is consumed during peak loads causing disruptions
Solution Approach 1:
The system extracts only the essential elements needed for synchronization - metadata, change indicators, and differential data - from complete data blocks. This extraction process maintains data integrity for the purposes of remote mirroring while consuming minimal network bandwidth, avoiding disruptions during peak loads.
Solution Approach 2:
The patent applies partial action by transmitting only the necessary portion of data information (changes and metadata) rather than complete data blocks. This partial transmission is sufficient to maintain synchronized mirrors while leaving abundant network bandwidth available for other operations during peak load periods.
Data Source
AI summary
In a synchronous remote mirroring system, as a host computer writes data to primary storage in a primary data storage system, remote copy data is transferred from the primary data storage system to a secondary storage system in which secondary storage is maintained as a remote mirror of the primary storage. The primary data storage system performs data reduction upon the remote copy data prior to transmitting the remote copy data in a reduced to the secondary data storage system. The secondary data storage system returns an acknowledgement of receipt of the remote copy data upon receipt of the remote copy data in the reduced form, and later reverses the data reduction upon the remote copy data in the reduced form to produce data written to the secondary storage to maintain the secondary storage as the remote mirror of the primary storage.