--- title: "Install a Failover Cluster Instance" description: Learn to install a SQL Server failover cluster. Create and configure a failover cluster instance by running SQL Server Setup. author: MashaMSFT ms.author: mathoma ms.date: 08/25/2025 ms.service: sql ms.subservice: failover-cluster-instance ms.topic: how-to ms.custom: - intro-installation --- # Install a SQL Server failover cluster [!INCLUDE [SQL Server](../../../includes/applies-to-version/sqlserver.md)] To install a [!INCLUDE[ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster, you must create and configure a failover cluster instance by running [!INCLUDE[ssNoVersion](../../../includes/ssnoversion-md.md)] Setup. > [!NOTE] > [!INCLUDE [sssql25-md](../../../includes/sssql25-md.md)] failover cluster instance installation [fails if TLS 1.2 is disabled on the machine](../../sql-server-2025-known-issues.md#sql-server-2025-installation-fails-when-tls-12-is-disabled). ## Install a failover cluster To install a failover cluster, you must use a domain account that has local administrator rights and permission to sign on as a service and act as part of the operating system on all nodes in the failover cluster. 1. To install, configure, and maintain a [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster, use [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Setup. - Identify the information you need to create your failover cluster instance (for example, cluster disk resource, IP addresses, and network name) and the nodes available for failover. For more information, see: - [Before installing failover clustering](before-installing-failover-clustering.md) - [Security considerations for a SQL Server installation](../../install/security-considerations-for-a-sql-server-installation.md) - You must complete the configuration steps before you run the [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Setup program. Use the Windows Cluster Administrator to complete them. You must have one Windows server failover cluster group for each failover cluster instance that you want to configure. - You must ensure that your system meets minimum requirements. For more information on specific requirements for a [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster, see [Before installing failover clustering](before-installing-failover-clustering.md). 1. Add or remove nodes from a failover cluster configuration without affecting the other cluster nodes. For more information, see [Add or remove nodes in a SQL Server failover cluster (Setup)](add-or-remove-nodes-in-a-sql-server-failover-cluster-setup.md). - All nodes in a failover cluster must be of the same platform, either 32-bit or 64-bit, and must run the same operating system edition and version. Also, 64-bit [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] editions must be installed on 64-bit hardware running the 64-bit versions of Windows operating systems. There's no WoW64 support for failover clustering in this release. 1. Specify multiple IP addresses for each failover cluster instance. You can specify multiple IP addresses for each subnet. If the multiple IP addresses are on the same subnet, [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Setup sets the dependency to `AND`. If you're clustering nodes across multiple subnets, [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Setup sets the dependency to `OR`. 1. SQL Server failover cluster instance (FCI) requires the cluster nodes to be domain joined. The following configurations aren't supported: - SQL FCI on workgroup clusters - SQL FCI on a multi-domain cluster - SQL FCI on domain + workgroup clusters - SQL FCI when Read Only Domain Controllers (RODC) are available ## SQL Server failover cluster installation options ##### Option 1: Integrated installation with Add Node [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] integrated failover cluster installation consists of two steps: 1. Create and configure a single-node [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster instance. At the completion of a successful configuration of the node, you have a fully functional failover cluster instance. At this point, it doesn't support high availability because there's only one node in the failover cluster. 1. On each node to be added to the [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster, run Setup with Add Node functionality to add that node. ##### Option 2: Advanced/Enterprise installation [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Advanced/Enterprise failover cluster installation consists of two steps: 1. On each node that will be part of the [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster, run Setup with Prepare Failover Cluster functionality. This step prepares the nodes ready to be clustered, but there's no operational [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] instance after you complete this step. 1. After the nodes are prepared for clustering, run Setup on the node that owns the shared disk with the Complete Failover Cluster functionality. This step configures and completes the failover cluster instance. After you complete this step, you have an operational [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster instance. > [!NOTE] > Either installation option allows for multi-node [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster installation. You can use Add Node to add additional nodes for either option after a [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster is created. > [!IMPORTANT] > The operating system drive letter for [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] installation locations must match on all the nodes added to the [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] failover cluster. #### IP address configuration during setup [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] Setup lets you set or change the IP resource dependency settings during the following actions: - Integrated installation - [Create a new SQL Server failover cluster (Setup)](create-a-new-sql-server-failover-cluster-setup.md) - Complete Failover Cluster (advanced installation) - [Create a new SQL Server failover cluster (Setup)](create-a-new-sql-server-failover-cluster-setup.md) - Add Node - [Add or remove nodes in a SQL Server failover cluster (Setup)](add-or-remove-nodes-in-a-sql-server-failover-cluster-setup.md) - Remove Node - [Add or remove nodes in a SQL Server failover cluster (Setup)](add-or-remove-nodes-in-a-sql-server-failover-cluster-setup.md) > [!NOTE] > IPv6 IP addresses are supported. If you configure both IPv4 and IPv6 addresses, the two versions are treated like different subnets, and IPv6 is expected to come online first. ##### SQL Server multi-subnet failover cluster You can set `OR` dependencies when the nodes on the cluster are on different subnets. However, each node in the [!INCLUDE [ssNoVersion](../../../includes/ssnoversion-md.md)] multi-subnet failover cluster must be a possible owner of at least one of the IP addresses specified. ## Related content - [Before Installing Failover Clustering](before-installing-failover-clustering.md) - [Create a New Always On Failover Cluster Instance (Setup)](create-a-new-sql-server-failover-cluster-setup.md) - [Install and configure SQL Server on Windows from the command prompt](../../../database-engine/install-windows/install-sql-server-from-the-command-prompt.md) - [Upgrade a failover cluster instance](../windows/upgrade-a-sql-server-failover-cluster-instance.md)