three az design

The three az design tag covers a specific Windows Server cluster architecture that spans three AWS Availability Zones. The primary content discusses running a three-node SQL Server Failover Cluster Instance (FCI) on EC2 using Storage Spaces Direct (S2D) with locally attached EBS volumes. This design provides true multi-AZ resilience for Windows Server clusters, avoiding the constraints of two-AZ or single-AZ setups. The material includes architecture overviews, prerequisites, PowerShell-centric deployment steps, and analysis of operational tradeoffs, licensing, performance tuning, and failure modes. It is aimed at Windows administrators and DBAs evaluating high-availability SQL Server deployments on AWS.