You can upgrade an existing Network Load Balancing (NLB) cluster running Windows Server 2003 to Windows Server 2008 or Windows Server 2008 R2 by taking the entire cluster offline and upgrading all the hosts, or you can leave the NLB cluster online and perform a rolling upgrade. A rolling upgrade entails taking individual cluster hosts offline one at a time, upgrading each host, and returning the host to the cluster. You continue upgrading individual cluster hosts until the entire Windows Server 2003 cluster is upgraded. A rolling upgrade allows the cluster to continue running during the upgrade.

The decision to use rolling upgrades is based on the applications and services running on your existing cluster. If the applications and services support rolling upgrades, then perform a rolling upgrade on the existing cluster. Otherwise, perform the upgrade process recommended for the applications and services running on the cluster.

This section covers the following areas:

Preparing to upgrade the Network Load Balancing cluster

Upgrading the Network Load Balancing cluster