Types of Replication Methids

There are two methods by which we categorize replication:

1. Commit Synchronization Replication
2. Directional Replication

Commit Synchronization Replication:

 This determines the way in which the changes are implemented on the Source and Target site. It can be either:

1. Synchronous Replication flow
2. Asynchronous Replication flow

In the case of Synchronous Replication Flow the changes  are implemented on the source side only after they have been implemented on all the other sites. In case the changes fail to be applied in any of the targets then the changes are rolled back on all the nodes including the source.





Asynchronous Replication means that the changes are applied on the source irrespective of whether they are successfully implemented on the target side on or not. If the changes are not successful in any of the target sites then deferred commit is implemented i.e. the logs for applying the changes to the failed site are generated and maintained at the source site for applying them when the failed site becomes available.

Note: Synchronous and Asynchronous replication are mutually exclusive.

Directional Flow:

It specifies the direction in which the changes are applied. There are basically two types:

1. Unidirectional flow
2. Bidirectional flow

The Unidirectional flow generally takes place between a Master Node and a Client Node. Hence generally changes are not allowed in the target side. If changes are allowed in the target side then there might be inconsistency and might need conflict resolution implemented to allow future replication.

The Birectional Flow generally takes place between Master-Master nodes and if the transmission is of type asynchronous then it might cause data inconsistency.




Note: Unidirectional and Bidirectional flow are mutually exclusive.