Migrating Existing Clusters
Your organization might have applications and services that currently run on Windows NT 4.0 or Windows 2000 clusters. If you want these applications and services to take advantage of the improved security and performance of Windows Server 2003, and if you also want to run these applications on newly installed Windows Server 2003 servers, you can migrate the applications and servers from existing clusters to newly installed Network Load Balancing clusters.
The migration process is appropriate in the following situations:
You want to migrate one WLBS or Network Load Balancing cluster to a target Network Load Balancing cluster.
You want to consolidate multiple WLBS or Network Load Balancing clusters onto a target Network Load Balancing cluster.
Migrating WLBS clusters from Windows NT 4.0 or Network Load Balancing clusters from Windows 2000 requires only minimal effort for Network Load Balancing. The majority of the migration effort involves the applications and services running on the cluster. The process for migrating an existing cluster to a target Network Load Balancing cluster running Windows Server 2003 is shown in Figure 9.11.
Figure 9.11 Migrating Existing Clusters
Migrate your WLBS or Network Load Balancing cluster by using the information documented in the "NLB Cluster Host Worksheet" that your design team completed for each cluster host during the design process.
Network Load Balancing Migration Assumptions
The Network Load Balancing migration process to Windows Server 2003 assumes the following conditions:
Your applications and services are running on an existing cluster running WLBS (on Windows NT 4.0) or Network Load Balancing (on Windows 2000).
You are installing a new Network Load Balancing cluster as the target cluster.
Your applications and services are compatible with Windows Server 2003.
In addition to compatibility with Network Load Balancing, the applications and services must be compatible with Windows Server 2003. For help in determining if your application is compatible with Windows Server 2003, use the Windows Application Compatibility Toolkit on the Windows Server 2003 Deployment Kit companion CD.
For information about the migration process for the application or service running on your cluster, see "Additional Resources for Deploying Network Load Balancing" later in this chapter.
Network Load Balancing Migrations and Consolidations
In addition to migrating an existing cluster to the target cluster, you can use the Network Load Balancing migration process to consolidate multiple existing clusters to the target cluster. The consolidation process is identical to the migration process, except that, for each migration, you are migrating applications and services that formerly ran on multiple clusters onto a single target cluster.
As a part of consolidation, the port rules and cluster virtual IP addresses from all the source clusters must be created on the target cluster. For each cluster that you migrate, you must create port rules on the target cluster that handle the client traffic in the same manner as the traffic was handled on the source cluster. For more information about the migration of port rules, see "Migrating to the Target Cluster" later in this chapter.