Getting Started with SQL Server 2008 Failover Clustering

SQL Server Setup

previous page next page

Failover clustering in SQL Server provides high-availability support for an entire SQL Server instance. For example, you can configure a SQL Server instance on one node of a failover cluster to fail over to any other node in the cluster during a hardware failure, operating system failure, or a planned upgrade.

A failover cluster is a combination of one or more nodes (servers) with two or more shared disks, known as a resource group. The combination of a resource group, along with its network name, and an internet protocol (IP) address that makes up the clustered application or server, is referred to as a failover cluster or a failover cluster instance. A SQL Server failover cluster appears on the network as if it were a single computer, but has functionality that provides failover from one node to another if the current node becomes unavailable. A failover cluster appears on the network as a normal application or single computer, but it has additional functionality that increases its availability.

Failover clustering has a new architecture and new work flow for all Setup scenarios in SQL Server 2008. The two options for installation are Integrated installation and Advanced/Enterprise installation. Integrated installation creates and configures a single-node SQL Server failover cluster instance. Additional nodes are added using add node functionality in Setup. For example, for Integrated installation, you run Setup to create a single-node failover cluster. Then, you run Setup again for each node you want to add to the cluster. Advanced/Enterprise installation consists of two steps. The Prepare step prepares all nodes of the failover cluster to be operational. Nodes are defined and prepared during this initial step. After you prepare the nodes, the Complete step is run on the active node—the node that owns the shared disk—to complete the failover cluster instance and make it operational.

When to Use Failover Clustering

Use failover clustering to:

Installing Failover Clustering

To use failover clustering, you must follow specific installation steps.

To install, configure, and maintain a SQL Server failover cluster, use SQL Server Setup.Use SQL Server Setup in a failover cluster to do the following:

  • Install SQL Server to create a failover cluster.
    Before installing failover clustering, you must ensure that your system meets minimum requirements, and configure the Microsoft Cluster Service (MSCS). For more information on specific requirements for a failover cluster, see Before Installing Failover Clustering.
    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 SQL Server editions must be installed on 64-bit hardware running the 64-bit versions of Windows operating systems. There is no WOW64 support for failover clustering in this release.
  • Add or remove nodes from a failover cluster configuration without affecting the other cluster nodes. For more information, see How to: Add or Remove Nodes in a SQL Server Failover Cluster (Setup).
  • Specify multiple IP addresses for each failover cluster instance. You can specify multiple IP addresses for each server, allowing you to use all available network IP subnets. SQL Server limits you to one IP address per network. This provides alternative network connections if one subnet fails.

Failover Clustering Support

In SQL Server, the number of nodes supported for failover clustering depends on the operating system and the edition of SQL Server. For a list of tools, features, and services supported with SQL Server failover clustering, see Features Supported by the Editions of SQL Server 2005.

See Also

previous page start next page