Hello,

I have an environment where I have an alwayson availability group consisting of 2 replicas and a witness servers and holding 3 sql instances.

We are planning to have DR site and on the DR site we want to build the same availability group and replicate between them.

The 2 AG are independent and each will have 2 replicas. in the main site we will an application farm connected to AG1 and on the DR we are going to have application farm connected to AG2 that's why a multi subnet alwayson cluster is not usefule in my case.

Is that possible and what method shall we use to achieve this goal it will be great if there is an article that describes this procedure.

Hi Najwan,

Regardless of the recommendations you are going to need a multi subnet windows failover cluster that will stretch across both data centers.

1. You could have two AGs configured across a multi subnet Windows Failover Cluster. This way you have secondary replicas in the other data center that is replicating the data for you.  This would be the easiest way to replicate the data.
2. You also could have two FCI's one in each data center and then have an AG on top of the FCIs to replicate data changes across data centers. 

You mention replication above but I assume you just mean have transactional data go across both data centers.  SQL Server Replication (Transactional/ Merge / Snapshot / P2P) could be used but would require additional management and its requirements might not make it available for you plus AGs are an much easier way to have a full database copied on a transactional basis.  For example, you must have a primary key for every table you would want to replicate with transactional replication.

As requested here are some great links for more reading information:

Types of Replication -> https://msdn.microsoft.com/en-us/library/ms152531.aspx?f=255&MSPPError=-2147217396

FCIs in AGs -> https://msdn.microsoft.com/en-us/library/JJ215886.aspx

AGs for Disaster Recovery in Multiple Data Centers -> https://msdn.microsoft.com/en-us/library/jj191711.aspx