Determining Domain Migration Strategies

Transitioning to File Replication Service

Windows NT Server provided a replication facility known as LAN Manager Replication Service. The File Replication service (FRS) in Windows 2000 Server replaces the LAN Manager Replication Service.

Note

Windows 2000 Server does not support LAN Manager Replication Service in mixed or native mode, so if you have been using LAN Manager Replication, you need to include a strategy in your upgrade plan for moving to FRS to provide the same functionality.

LAN Manager Replication Service Process

LAN Manager Replication Service uses the concept of import and export directories. You configure LAN Manager Replication Service by selecting a server on which to host an export directory and a number of servers to host import directories. The servers hosting the directories do not need to be domain controllers; they can be ordinary member servers. Figure 10.5 illustrates the LAN Manager Replication Service process.

Enlarge figure

Figure 10.5 The LAN Manager Replication Service Process

The FRS Process

FRS in Windows 2000 Server is automatically configured so that every domain controller has a replicated System Volume (SYSVOL). Any change you make to a logon script stored in the SYSVOL of any domain controller is replicated in multiple-master fashion to other domain controllers. Unlike LAN Manager Replication, where ordinary member servers can host import and export directories, with FRS only domain controllers can host the SYSVOL. Figure 10.6 illustrates the FRS process.

Enlarge figure

Figure 10.6 The FRS Process

Maintaining LAN Manager Replication Service in a Mixed Environment

During an upgrade, you can maintain a mixed environment of Windows NT BDCs and member servers operating with Windows 2000 domain controllers. Because Windows 2000 Server does not support LAN Manager Replication Service, maintaining in a mixed environment could be an issue. To provide this support, you need to create a bridge between LAN Manager Replication Service and FRS so that both services can operate. You do this by selecting a Windows 2000 domain controller to copy the files that will be replicated to the Windows NT export directory. The copying is done through a regularly scheduled script called L-bridge.cmd.

Note

Do not confuse the term mixed environment with mixed mode, which refers to the PDC and zero or more BDCs within a Windows 2000 domain. A mixed environment refers to a Windows 2000 domain in mixed or native mode and containing pre–Windows 2000 clients or servers.

Setting up the Bridge Between LAN Manager Replication Service and FRS

Before you set up the bridge between LAN Manager Replication Service and FRS, you must do the following:

Determine the Windows NT export server for the directory in question.
Select a Windows 2000 computer that can push files to that directory.

It is recommended that you manually disable the LAN Manager Replication Service from Services in Control Panel before each domain controller or member server upgrade. Though not recommended, you can disable the Directory Replicator from MMC after the upgrade.

To upgrade the export server before upgrading to Windows 2000, perform the following steps:

Run SrvMgr.exe on the current export server and remove the export directory.
From the new export server, add the export directory to the export list through SrvMgr.exe.

A batch file provides the link between the Windows NT scripts directory and the Windows 2000 System Volume. The benefit of this approach is that the two replication mechanisms are physically separated from one another, thus no legacy services are being introduced on the Windows 2000 domain controller.

To set up a batch file for the bridge between LAN Manager Replication Service and FRS, perform the following steps:

Select a Windows 2000 domain controller.
Create a batch file named L-bridge.cmd that copies the logon scripts to the Windows NT export server, as in the following example.

xcopy \\domain.com\Sysvol\domain.com\scripts \\Srv3\Export\scripts /s /D

Note that the /D command line switch tells xcopy to copy only newer files. The /s command line switch tells xcopy to copy the directory and all subdirectories, provided they are not empty.

Using the Windows 2000 Schedule service, set up a reasonable interval for the batch file to be run. An interval of every two hours is more than sufficient, particularly because using the /D option prevents the creation of unnecessary file copies.

A sample version of L-bridge.cmd is included on the Windows 2000 Resource Kit compact disc.

Keeping LAN Manager Replication Service Available During Upgrade

To keep LAN Manager Replication Service available during upgrade, you need to upgrade the server hosting the export directory only after all the other servers hosting import directories have been upgraded. If the server hosting the export directory is the PDC, you need to select a new export server and reconfigure LAN Manager Replication Service. It is recommended that the new server you select is one that you believe will be the last server to be upgraded to Windows 2000; otherwise, you will need to select another export server and go through the process again, since servers are upgraded sequentially.