If you are considering deploying your own Microsoft SQL Server instances in AWS EC2, you have some decisions to make regarding the resiliency of the solution. Sure, AWS will offer you a 99.99% SLA on your Compute resources if you deploy two or more instances across different availability zones. But don’t be fooled, there are a lot of other factors you need to consider when calculating your true application availability. I recently blogged about how to calculate your application availability in the cloud. You probably should have a quick read of that article before you move on.
When it comes to ensuring your Microsoft SQL Server instance is highly available, it really comes down to two basic choices: Always On Availability Group (AG) or SQL Server Failover Cluster Instance (FCI). If you are reading this article I’m making an assumption you are well aware of both of these options and are seriously considering using a SQL Server FCI instead of a SQL Server Always On AG.