Failover Clustering

Failover Clustering is the underlying technology that enables highly available virtual machines in Hyper-V. A virtual machine that is made highly available or created with that feature becomes a cluster role that is visible in Failover Cluster Manager.

There are 3 steps that need to be performed:

Installation of the feature and management tools
Cluster validation must be passed.
Creating the Failover Cluster

Installation

Failover Clustering can be installed without any management tools, such as when all management is handled elsewhere and on Windows Server Core.

Install-WindowsFeature Failover-Clustering

GUI and PowerShell management tools can also be installed.

Install-WindowsFeature RSAT-Clustering-Mgmt
Install-WindowsFeature RSAT-Clustering-PowerShell

You can also install the feature and the management tools with the -IncludeManagementTools parameter.

Validation

The test-cluster cmdlet can be used to validate the cluster.

In Failover Cluster Manager, click Validate Configuration in the Actions pane, add the potential cluster members.
Run all the tests and follow up on any settings that are flagged.
If the validation passes, check the box to create the cluster and select finish.
This will launch the Create Cluster Wizard and include all of the nodes that passed validation. A cluster name and IP address is required because a computer object will be created in Active Directory.
In Windows Server 2025 there is a new default cluster role, the User Manager Group, which enables Windows Admin Center management from accounts in Entra ID (Azure AD).
Virtual Machines are not part of a cluster when using Hyper-V Manager. Those machines can be converted into cluster roles with Configure Role in Failover Cluster Manager, or with the following command in PowerShell:
```
Add-ClusterVirtualMachineRole -VirtualMachine VM1
```
When creating a new VM, Failover Cluster Manager will combine the VM creation with making it highly available.