Database Availability Group

Note

End of support notice: On May 1, 2025, AWS Launch Wizard will discontinue support for Amazon Elastic Kubernetes Service, Microsoft Internet Information Services, and Microsoft Exchange Server. After May 1, 2025, you can no longer use AWS Launch Wizard to access these workloads.

A failover cluster is automatically created for the database availability group (DAG). Launch Wizard will carry out this task when deploying the second node. The following Windows PowerShell commands to complete this task:

Install-WindowsFeature failover-clustering –IncludeManagementTools
New-DatabaseAvailabilityGroup -Name DAG -WitnessServer FileServer -WitnessDirectory C:\DAG
Add-DatabaseAvailabilityGroupServer -Identity DAG -MailboxServer ExchangeNode1
Add-DatabaseAvailabilityGroupServer -Identity DAG -MailboxServer ExchangeNode2

The first command runs on each instance during the bootstrapping process. It installs the required components and management tools for the failover clustering services. The rest of the commands run near the end of the bootstrapping process on the second node and are responsible for creating the cluster and for defining the server nodes and IP addresses.

By default, Launch Wizard configures an even number of servers in the cluster. You need a third resource to maintain a majority vote to keep the cluster online if an individual server fails. For this, Launch Wizard uses a dedicated file share witness instance, which can be either a domain-joined server, or a third Exchange node, which cannot be part of the DAG itself. Launch Wizard creates a Dedicated Instance in the first Availability Zone to act as the file share witness.

For production environments, you can also set the Third AZ parameter to witness to create a Dedicated Instance with a file share in a third Availability Zone. Alternatively, you can use any domain-joined server for this task, but this configuration option is not included for the deployment. If you set the Third AZ parameter to full, Launch Wizard keeps the quorum settings to the default node majority and creates a third Exchange Server node in the third Availability Zone.

Some AWS Regions support only two Availability Zones. For a current list, see AWS Global Infrastructure. The Launch Wizard deployment ends after creating the DAG and adding the two Exchange nodes to it. When the deployment is complete, you can create additional databases, and make them highly available, by creating copies on the second nodes. This process is covered in the Post-deployment steps portion of this guide.