Asynchronous VS Synchronous Replication

Asynchronous vs Synchronous Replication

There are broadly two strategies that can be adopted for replicating changes from the leader to its followers. These are:

  • Asynchronous Replication

  • Synchronous Replication

The two can be combined to form a hybrid strategy, sometimes called semi-synchronous replication.

Asynchronous Replication

In the leader-based replication model, there is a spectrum that defines how replication from the leader to the followers takes place. On one end of the spectrum is the asynchronous replication, which involves the leader registering a change locally and then immediately returning a success message in response to a client’s write request. The leader doesn’t wait for the change to propagate to its followers before informing the client that the client’s write request has been successfully processed. The hope is that the leader will be able to transmit the change to its followers without crashing or some other issue such as a network partition occurring. The pictorial representation demonstrates a fully asynchronous replication scenario:

  1. Writes are accepted at the leader only.

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