Assigning Server Roles | Migrating from Microsoft Windows NT Server 4.0 to Windows Server 2003

As you plan your migration from a Windows NT 4.0 environment to Windows Server 2003, it is important to plan your future server role assignments. This involves completing the following steps:

Documenting the servers in your current environment and the services that each server provides.
Assigning the server roles in your new environment, and documenting those assignments.
Performing basic capacity planning to verify that you have sufficient capacity on your servers to host the assigned server roles.
Evaluating the existing network configuration, including IP address and network adapter information for each server.

Document Servers and Services in Your Current Environment

Identify the servers in your existing Windows NT 4.0 domain, and document the services that each server provides. Be sure to identify servers that provide the LAN Manager Replication (LMRepl) service, Remote Access Service, and file service, because you will need to perform tasks prior to upgrading to ensure the continued functionality of these services and access to resources for clients .

You can create a simple table to document your servers and services. Table 1.2 shows the servers and services documentation for Fabrikam, Inc.

Table 1.2: Servers and Services in the Current Environment for Fabrikam
Server Name	Server Role	Services
SEA-FAB-DC01	PDC	WINS, DHCP, LMRepl export server
SEA-FAB-DC02	BDC	LMRepl import server, RAS server
SEA-FAB-DC03	BDC	New BDC deployed on upgradeable hardware.
SEA-FAB-MS01	Member server	File server, print server

For more information about the effect of upgrading to Windows Server 2003 Active Directory on WINS, DHCP, the RAS service, and the LMRepl service, see Upgrading to Windows Server 2003 Active Directory in this book.

Assign Server Roles in the New Environment

To assign server roles in your new environment, first assign the domain controllers in your existing environment roles in your new Windows Server 2003 domain. Then, decide where to place other services in the new domain.

Domain Controller Roles

Assign the existing Windows NT 4.0 “based domain controllers roles that they will assume in the new Windows Server 2003 domain after the upgrade is complete. Assign one of the following three roles to Windows NT 4.0 “based domain controllers in a Windows Server 2003 domain:

Windows Server 2003 “based domain controller . Assign the role of Windows Server 2003 “based domain controller to the Windows NT 4.0 PDC and to any BDCs that meet the appropriate hardware and software requirements.
Rollback server . Assign the role of rollback server in the Windows Server 2003 domain to a Windows NT 4.0 BDC that does not meet the Windows Server 2003 domain controller hardware requirements.
Windows Server 2003 “based member server . Assign the role of member server in the Windows Server 2003 domain to a Windows NT 4.0 “based BDC that does not meet the Windows Server 2003 domain controller hardware requirements.

It is helpful to document this information in a table. List in the table the Windows NT 4.0 “based domain controllers in your domain, whether they meet the hardware requirements for Windows Server 2003, the current role of the domain controller, and the role for the domain controller after you upgrade the domain.

Fabrikam documented their domain controller role assignments as shown in Table 1.3.

Table 1.3: Domain Controller Role Assignments
Domain Controller Name	Meets hardware requirements?	Role before upgrade	Role after upgrade
SEA-FAB-DC01	Yes	Windows NT 4.0 PDC	Windows Server 2003 domain controller
SEA-FAB-DC02	No	Windows NT 4.0 BDC	Rollback server
SEA-FAB-DC03	Yes	Windows NT 4.0 BDC	Windows Server 2003 domain controller

Server Roles

Decide where to place all services on both domain controllers and member servers after you migrate your environment to Windows Server 2003. This decision depends on whether your existing server hardware meets the requirements to run Windows Server 2003. Generally, if a server on which a service is running meets the hardware requirements, you can either upgrade it in place or migrate it to another server; if the server on which the service is running does not meet hardware requirements, you must migrate the service to or reinstall the service on a different server. You can also choose to migrate services to different servers to consolidate them on fewer servers, or, alternatively, to separate them.

Server Role Assignment if All Windows NT 4.0 Domain Controllers Meet Hardware Requirements

If your Windows NT 4.0 “based domain controllers are running other services, such as DHCP, WINS, File and Print, or IIS, then determine whether you want to upgrade these services in place on the existing hardware, or migrate them to one or more separate domain controllers or member servers. If a server is running the Remote Access Service, you must migrate the service to a server running Windows Server 2003 before you upgrade the domain controller. For more information about migrating these server roles to Windows Server 2003, see the following chapters in this book:

Upgrading and Migrating WINS and DHCP Servers to Windows Server 2003
Migrating File and Print Servers to Windows Server 2003
Migrating to Dial-up and VPN Remote Access Servers Running Windows Server 2003
Migrating Web Sites from IIS 4.0 to IIS 6.0

Server Role Assignment if the PDC Does Not Meet Hardware Requirements

If the PDC does not meet hardware requirements, deploy a new Windows NT 4.0 BDC on new server hardware. You can then promote the new BDC to the PDC, and this computer will become your first Windows 2003 domain controller.

If you have other server roles running on the original PDC, such as DHCP, WINS, File and Print, RAS, or IIS, then develop a plan to migrate these roles from the original PDC to the server of your choice in your Windows Server 2003 environment. For more information about migrating these server roles, see the following chapters in this book:

Upgrading and Migrating WINS and DHCP Servers to Windows Server 2003
Migrating File and Print Servers to Windows Server 2003
Migrating to Dial-up and VPN Remote Access Servers Running Windows Server 2003
Migrating Web Sites from IIS 4.0 to IIS 6.0

Server Role Assignment if a BDC Does Not Meet Hardware Requirements

After you deploy your first Windows Server 2003 domain controller, you can install additional new Windows Server 2003 domain controllers and member servers. You can then migrate any services on the original BDC to the first Windows Server 2003 domain controller or to the new server of your choice.

Example: Server Role Assignments for Fabrikam

Fabrikam assigned their server roles as shown in Table 1.4.

Table 1.4: Server Role Assignments
Server Name	Meets hardware requirements?	Role before upgrade	Role after upgrade
SEA-FAB-DC01	Yes	Windows NT 4.0 PDC, WINS server, DHCP server	Windows Server 2003 domain controller DNS server WINS server DHCP server File server, print server
SEA-FAB-DC02	No	Windows NT 4.0 BDC, RAS server	Rollback server
SEA-FAB-DC03	Yes	Windows NT 4.0 BDC	Windows Server 2003 domain controller DNS server WINS server DHCP server Routing and Remote Access Server File server, print server
SEA-FAB-MS01	No	File server, print server	None, server not upgradeable

One of the goals for Fabrikam is to consolidate all services on two servers in Seattle. Because two domain controllers are required, both servers were assigned the domain controller role. To achieve both redundancy and standardization, both servers were also assigned the roles of DNS server, WINS server, DHCP server, file server, and print server. On SEA-FAB-DC01, WINS and DHCP were already running, so they will be upgraded in place. The services that were running on servers that will not be upgraded (RAS, file, and print) were assigned to be migrated to SEA-FAB-DC03.

Plan for Server Capacity

Domain controller capacity planning for smaller organizations is straightforward. For a single domain with up to 2999 users and one location, you will need two domain controllers, each with a Uniprocessor 850 megahertz (MHz) or higher CPU. If you have more than one location, you will need an additional domain controller for each location.

If you have other services running on the domain controllers, you might want to add more CPU, RAM, or disk space to improve performance. File servers have capacity requirements that vary depending on the data in your organization. For information about planning for file server capacity, see Migrating File and Print Servers to Windows Server 2003 in this book.

Example: Sequence of Migration Tasks for Fabrikam

After they assigned server roles to server hardware and established their capacity requirements, the IT department for Fabrikam listed the sequence of tasks to be performed in order to place the server roles. These include the following:

Purchase one new server with sufficient capacity to run the services assigned to SEA-FAB-DC03.
Deploy SEA-FAB-DC03 as a new member server running Windows Server 2003 in the Windows NT 4.0 environment. (They will install Active Directory on this server after they upgrade the PDC, making it the second domain controller in the Windows Server 2003 domain.)
Migrate the Remote Access Service currently running on SEA-FAB- DC02, and the file and print services currently running on SEA-FAB- MS01, to SEA-FAB-DC03.
Upgrade the domain to Windows Server 2003 Active Directory, following the sequence of tasks in the Upgrading to Windows Server 2003 Active Directory chapter in this book.

The Fabrikam IT department chose to deploy their new server, SEA-FAB- DC03, as a member server in the Windows NT 4.0 environment, rather than waiting until after the upgrade to deploy it. This allowed them to migrate the Remote Access Service from the BDC, SEA-FAB-DC02, and take the BDC offline as their rollback server. It also enables them to gain experience with the administration tools in Windows Server 2003 before they upgrade their domain.

Evaluate the Existing Network Configuration

Evaluate the existing network configuration for your Windows NT 4.0 domain to determine whether it is sufficient for your new Windows Server 2003 domain. Some network adapter drivers that are included with earlier versions of the operating system are not distributed with Windows Server 2003. If you attempt to upgrade a Windows NT 4.0 “based server to Windows Server 2003 and a network adapter is installed for which a driver is not provided, your network information might be lost or detected incorrectly during the upgrade.

Note	You can install device drivers that are not included on the Windows Server 2003 operating system CD from the vendor s Web site.

Identify the type of network adapter that each server in your domain uses. Also, include the TCP/IP configuration information for each server, including IP address, subnet mask, and default gateway. You can run the ipconfig command at the command line to determine IP address, subnet mask, and default gateway. For more information about the ipconfig command, type ipconfig /? at the command line.

To determine whether the network adapter is supported by Windows Server 2003, see the Windows Server Catalog link on the Web Resources page at http://www.microsoft.com/windows/reskits/webresources.

Table 1.5 shows the network configuration information for Fabrikam.

Table 1.5: Fabrikam Server Network Configuration
Domain Controller Name	Network Adapter	IP Address	Subnet Mask	Default Gateway
SEA-FAB-DC01	Netgear FA310TX Fast Ethernet Adapter	172.16.12.2	255.255.252.0	172.16.12.1
SEA-FAB-DC03	IBM Netfinity 10/100 Ethernet Adapter	172.16.12.3	255.255.252.0	172.16.12.1
SEA-FAB-MS01	3COM Etherlink III LAN PC Card (3C589) (Ethernet)	172.16.12.14	255.255.252.0	172.16.12.1