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How rolling upgrades work

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

How rolling upgrades work

This topic describes rolling upgrades on server clusters. To decide whether you can perform a rolling upgrade, see Restrictions on rolling upgrades. For information about methods, restrictions, and alternatives to rolling upgrades, see the links at the end of this topic.

There are two major advantages to a rolling upgrade. First, there is a minimal interruption of service to clients. (However, server response time might decrease during the phases in which a fewer number of nodes handle the work of the entire cluster.) Second, you do not have to recreate your cluster configuration. The configuration remains intact during the upgrade process.

In this example, the rolling upgrade starts with two cluster nodes that are running Windows 2000 named Node 1 and Node 2. The following diagram depicts the process:

Overview of a rolling upgrade

Phase 1: preliminary

Each node runs Windows 2000 Advanced Server with the following software:

  • The Cluster service component, one of the optional components of Windows 2000 Advanced Server.

  • Applications that support a rolling upgrade. For more information, see the application documentation and Resource behavior during rolling upgrades.

At this point, your cluster is configured so that each node handles client requests (an active/active configuration).

Phase 2: upgrade node 1

Node 1 is paused, and Node 2 handles all cluster resource groups while you upgrade the operating system of Node 1 to Windows Server 2003, Enterprise Edition, and Windows Server 2003, Datacenter Edition.

You are now running a mixed version cluster. A mixed version cluster is a cluster in which the nodes are running different versions of the operating system. Although mixed version clusters are supported by Windows Server 2003, Enterprise Edition, and Windows Server 2003, Datacenter Edition, they are not the optimal configuration. It is recommended that you upgrade all nodes to the same operating system by completing the final two phases of the rolling upgrade.

When your cluster is in a mixed version state, it is recommended that you do not make any changes to the cluster configuration, such as adding or removing nodes. It is also recommended that you do not make changes to any of the cluster resources while your cluster is in a mixed version state.

Phase 3: upgrade node 2

Node 1 rejoins the cluster. Node 2 is paused and Node 1 handles all cluster resource groups while you upgrade the operating system on Node 2.

Phase 4: final

Node 2 rejoins the cluster, and you redistribute the resource groups back to the active/active cluster configuration.


  • If your goal is to have more than two nodes in the cluster, you must use Fibre Channel (not SCSI) for the cluster storage. Add the additional nodes after completing the rolling upgrade. Before adding additional nodes, confirm that your entire cluster solution is compatible with products in the Windows Server 2003 family by clicking the appropriate link in Support resources. Your cluster solution must be in the Cluster category of compatible hardware.

  • For cluster disks, you must use the NTFS file system and configure the disks as basic disks. You cannot configure cluster disks as dynamic disks, and you cannot use features of dynamic disks such as spanned volumes (volume sets). For more information, see Limitations of server clusters.

For more information about rolling upgrades, see:

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