What is the difference between synchronous and asynchronous replication?

Synchronous replication refers to the process of data being written to the primary storage system and then being immediately copied to the secondary storage system. This means that every write operation must be confirmed by both the primary and secondary storage systems before the write operation is considered to be completed. Synchronous replication ensures that data is fully replicated and consistent across all storage systems at all times, but it can introduce latency as it waits for confirmation from the secondary storage system.

On the other hand, asynchronous replication involves a delay between the write operation being performed on the primary storage system and the replication of that data to the secondary storage system. In asynchronous replication, the write operation is considered complete once it has been written to the primary storage system, and the replication to the secondary storage system occurs afterward. Asynchronous replication offers reduced latency and improved performance since the write operation is not delayed by waiting for the secondary storage confirmation. However, there may be a slight window of time where data on the secondary storage system is not consistent with the primary storage system.

In summary, synchronous replication prioritizes data consistency but may introduce latency, while asynchronous replication prioritizes performance and reduces latency but may have a slight delay in data consistency. The choice between the two depends on the specific requirements and priorities of the system or application.

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