Microsoft sql cluster server

Nodes and hosted applications are notified when failover occurs so that they may react appropriately. The Always On features provide integrated, flexible solutions that increase application availability, provide better returns on hardware investments, and simplify high availability deployment and management. Related resources are combined into a role , which can be made dependent upon other WSFC cluster resources. This type of instance depends on resources for storage and virtual network name.

The virtual network name resource depends on one or more virtual IP addresses, each in a different subnet. In the event of a failover, the WSFC service transfers ownership of instance's resources to a designated failover node. The SQL Server instance is then re-started on the failover node, and databases are recovered as usual. At any given moment, only a single node in the cluster can host the FCI and underlying resources. The shared disk storage volumes must be available to all potential failover nodes in the WSFC cluster.

An availability group consists of a primary availability replica and one to four secondary replicas that are maintained through SQL Server log-based data movement for data protection without the need for shared storage. The availability group and a corresponding virtual network name are registered as resources in the WSFC cluster. An availability group listener on the primary replica's node responds to incoming client requests to connect to the virtual network name, and based on attributes in the connection string, it redirects each request to the appropriate SQL Server instance.

In the event of a failover, instead of transferring ownership of shared physical resources to another node, WSFC is leveraged to reconfigure a secondary replica on another SQL Server instance to become the availability group's primary replica. The availability group's virtual network name resource is then transferred to that instance. At any given moment, only a single SQL Server instance may host the primary replica of an availability group's databases, all associated secondary replicas must each reside on a separate instance, and each instance must reside on separate physical nodes.

A Failover Cluster Instance FCI may be used together with an availability group to enhance the availability of an availability replica.

However, to prevent potential race conditions in the WSFC cluster, automatic failover of the availability group is not supported to or from an availability replica that is hosted on a FCI.

High availability for an Always On solution is accomplished though proactive health monitoring of physical and logical WSFC cluster resources, together with automatic failover onto and re-configuration of redundant hardware. A system administrator can also initiate a manual failover of an availability group or SQL Server instance from one node to another.

These policies, based on the severity, duration, and frequency of unhealthy cluster resource status and node responsiveness, can trigger a service restart or an automatic failover of cluster resources from one node to another, or can trigger the move of an availability group primary replica from one SQL Server instance to another.

Failover of an availability group replica does not affect the underlying SQL Server instance. Failover of a FCI moves the hosted availability group replicas with the instance. Each resource in a WSFC can report its status and health, periodically or on-demand. This means that client recovery time in multi-subnet failovers no longer depend on DNS update latencies. By default, the client tries the IP addresses in order.

This can help minimize the client recovery latency when failovers occur. With legacy client libraries or third party data providers, you cannot use the MultiSubnetFailover parameter in your connection string. To help ensure that your client application works optimally with multi-subnet FCI in SQL Server, try to adjust the connection timeout in the client connection string by 21 seconds for each additional IP address. This ensures that the client's reconnection attempt does not timeout before it is able to cycle through all IP addresses in your multi-subnet FCI.

Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Please rate your experience Yes No. On each node that is a possible owner of the new SQL Server failover cluster, follow the Prepare Failover Cluster setup steps that are listed in the Prepare section. On the additional nodes to be prepared, instead of following these steps, you can supply the autogenerated Configuration. This step prepares the nodes ready to be clustered, but there is no operational instance of SQL Server at the end of this step.

After the nodes are prepared for clustering, run Setup on one of the prepared nodes. This step configures and finishes the failover cluster instance. At the end of this step, you will have an operational SQL Server failover cluster instance and all the nodes that were prepared previously for that instance will be the possible owners of the newly created SQL Server failover cluster instance.

If you are creating a failover cluster instance that spans multiple subnets, Setup will detect the union of all the subnets across all nodes that have the SQL Server prepared failover cluster instance. You will be able to specify multiple IP addresses for the subnets. Each prepared node must be the possible owner of at least one IP address. If each of the IP addresses specified for the subnets are supported on all the prepared nodes, the dependency is set to AND.

If each of the IP addresses specified for the subnets are not supported on all the prepared nodes, the dependency is set to OR. Complete Failover Cluster requires that the underlying Windows Server failover cluster exists.

If the Windows Server failover cluster does not exist, Setup gives an error and exits. For more information about how to add nodes to or remove nodes from an existing failover cluster instance, see Add or Remove Nodes in an Always On Failover Cluster Instance Setup.

For more information about remote installation, see Supported Version and Edition Upgrades. Before Installing Failover Clustering.

You must have this information to create a new failover cluster instance. To install from a network share, browse to the root folder on the share, and then double-click Setup. For more information about how to install prerequisites, see Before Installing Failover Clustering.

The System Configuration Checker runs a discovery operation on your computer. To continue, Click OK.. The System Configuration Checker verifies the system state of your computer before Setup continues. After the check is complete, select Next to continue. On the Product key page, indicate whether you are installing a free edition of SQL Server, or whether you have a PID key for a production version of the product.

On the License Terms page, read the license agreement, and then select the check box to accept the license terms and conditions.

To help improve SQL Server, you can also enable the feature usage option and send reports to Microsoft. Select Next to continue. To end Setup, select Cancel. On the Feature Selection page, select the components for your installation. A description for each component group appears in the right pane after you select the feature name. You can select any combination of check boxes, but only Database Engine, Analysis Services in tabular mode, and Analysis Services in multidimensional mode support failover clustering.

Other selected components will run as a stand-alone feature without failover capability on the current node that you are running Setup on. You cannot add features to a failover cluster instance after creation. For example, you cannot add the PolyBase feature to an existing failover cluster instance.

Make note of what features are needed before beginning the installation of a failover cluster instance. The prerequisites for the selected features are displayed on the right-hand pane. SQL Server Setup will install the prerequisite that are not already installed during the installation step described later in this procedure. At this time it does not have high-availability because there is only one node in the failover cluster.

This step prepares the nodes ready to be clustered, but there is no operational SQL Server instance at the end of this step. 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.

At the end of this step, you will have an operational SQL Server failover cluster instance. Either installation option allows for multi-node SQL Server failover cluster installation. Add Node can be used to add additional nodes for either option after a SQL Server failover cluster has been created. You can set OR dependencies when the nodes on the cluster are on different subnets.