Applies toSQL Server 2016+ (Standard 2-node FCI or Enterprise) on Windows Server 2019/2022 EC2, FSx for Windows File Server Multi-AZ, FSx for NetApp ONTAP Multi-AZ
Why keep an FCI
- The whole instance fails over: logins, jobs, linked servers, SSIS catalog — no syncing objects between replicas.
- Standard edition supports a 2-node FCI (AG in Standard is limited to Basic AGs).
- Teams already operate FCIs on-premises; the same skills apply.
On AWS, shared storage comes from FSx, which is itself highly available across AZs.
1. Storage options
| Option | Protocol | Notes |
|---|---|---|
| FSx for Windows File Server (Multi-AZ) | SMB 3 continuously available shares | Simple; SQL Server data and logs on an SMB share; throughput capacity sized for SQL |
| FSx for NetApp ONTAP (Multi-AZ) | iSCSI LUNs (or SMB) | Block storage like a SAN; snapshots, SnapMirror for DR, storage efficiency |
2. Network and cluster design
- Two EC2 nodes in two AZs (different subnets) — a multi-subnet cluster.
- Each node gets secondary private IPs for the cluster IP and the SQL network name (one per subnet); the cluster uses these instead of a load balancer.
- Domain-joined (AWS Managed Microsoft AD or self-managed AD).
- Witness: file share witness on FSx, or a cloud witness (Azure storage) if allowed, or a third-AZ file share.
New-Cluster -Name sqlclu01 -Node sqlnode1, sqlnode2 -StaticAddress 10.10.1.50, 10.10.2.50 -NoStorage
Set-ClusterQuorum -FileShareWitness \\fsx-witness.corp.local\witness
3. Install SQL Server FCI
- FSx for Windows: during setup, point data and log directories to the SMB share (
\\amznfsxabc.corp.local\share\SQLData). The SQL service account needs full control on the share. - FSx for ONTAP: connect iSCSI LUNs to both nodes with MPIO, add them as cluster disks, then run SQL setup "New SQL Server failover cluster installation" on node 1 and "Add node" on node 2.
4. Migrate the data
- Backup/restore (via S3), log shipping, or a distributed AG from the on-premises instance to the FCI for minimal downtime.
- Copy instance objects with dbatools (
Copy-DbaLogin,Copy-DbaAgentJob, ...). - Cut over by updating the DNS alias to the new SQL network name.
5. Test failover
Move-ClusterGroup -Name "SQL Server (MSSQLSERVER)" -Node sqlnode2
Test node failure (stop the instance), AZ failure simulation, and FSx failover (FSx Multi-AZ fails over automatically; SQL may see a short IO pause).
6. DR
- FSx for ONTAP SnapMirror to a second region, or
- Log shipping / distributed AG to a DR instance in another region, or
- AWS Elastic Disaster Recovery for the nodes (check support for clustered setups).
Tip
Size FSx throughput capacity from your SQL IO baseline (MB/s and IOPS), not just storage size. An undersized FSx throughput tier is the most common cause of a slow FCI on AWS.