# SQL Server on Amazon EC2 architecture diagrams
<a name="architecture"></a>

This section provides architecture diagrams that illustrate the HA/DR strategies described in previous sections.

## Two-node HA/DR architecture with Always On availability group cluster (single-Region, Multi-AZ)
<a name="two-node-one-region"></a>

![\[Two-node HA/DR architecture with Always On availability group cluster (single-Region, Multi-AZ)\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/sql-server-ec2-ha-dr/images/two-node-ag.png)


## Three-node HA/DR architecture (single-Region, Multi-AZ)
<a name="three-node-one-region"></a>

![\[Three-node HA/DR architecture with Always On availability group cluster (single-Region, Multi-AZ)\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/sql-server-ec2-ha-dr/images/three-node-ag.png)


## Four-node HA/DR architecture with Always On distributed availability group cluster (multi-Region, Multi-AZ)
<a name="four-node-two-region"></a>

![\[Four-node HA/DR architecture with distributed Always On availability group cluster (multi-Region, Multi-AZ)\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/sql-server-ec2-ha-dr/images/four-node-dag.png)


## Three-node HA/DR architecture with single availability group (multi-Region)
<a name="three-node-two-region"></a>

![\[Three-node HA/DR architecture with basic Always On availability group cluster (multi-Region, Multi-AZ)\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/sql-server-ec2-ha-dr/images/three-node-two-regions.png)


## Three-node HA/DR architecture with log shipping (multi-Region)
<a name="log-shipping"></a>

![\[Three-node HA/DR architecture with basic Always On availability group cluster (multi-Region, Multi-AZ) and log shipping\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/sql-server-ec2-ha-dr/images/log-shipping.png)