What Is the Difference Between Synchronous Remote Replication and Asynchronous Remote Replication

Publication Date:  2016-11-28 Views:  77 Downloads:  0
Issue Description
What Is the Difference Between Synchronous Remote Replication and Asynchronous Remote Replication
Solution
Both synchronous remote replication and asynchronous remote replication can be used in disaster recovery solutions implemented by storage systems to back up data remotely. However, they are implemented in different ways and applicable to different service scenarios.
Implementation modes are describes as follows:
• Synchronous remote replication: When a host writes data to the primary LUN, a write request is also sent to the secondary LUN. After both LUNs return a response indicating a successful I/O write, the primary storage system sends the host a response indicating a successful I/O write, implementing real-time data synchronization between the primary LUN and the secondary LUN.
• Asynchronous remote replication: When writing data to the primary LUN, the primary storage system records the changed data. After the primary LUN returns a response indicating a successful write, the primary storage system sends the host a response indicating a successful write. Then, data synchronization is triggered by a user manually or by the system based on user-defined trigger conditions to ensure data consistency between the primary LUN and the secondary LUN.
Service scenarios are described as follows:
• Synchronous remote replication requires high bandwidth and low data latency. Therefore, synchronous remote replication is typically used in disaster recovery scenarios where the primary and secondary storage systems are adjacent to each other, such as the intra-city data backup and disaster recovery scenario.
• Asynchronous remote replication is not demanding on bandwidth and data latency. Therefore, asynchronous remote replication is applicable to disaster recovery scenarios where the primary and secondary storage systems are far away from each other or the network bandwidth is limited.

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