Understanding Migration Stages

Because SYSVOL is critical to the health and functionality of your domain, Windows does not provide a mechanism with which to convert replication of SYSVOL from FRS to DFS-R instantly. In fact, migration to DFS-R involves creating a parallel SYSVOL structure. When the parallel structure is successfully in place, clients are redirected to the new structure as the domain's system volume. When the operation has proven successful, you can eliminate FRS.

Migration to DFS-R thus consists of four stages or states:

• 0 (start) The default state of a domain controller. Only FRS is used to replicate SYSVOL.
• 1 (prepared) A copy of SYSVOL is created in a folder called SYSVOL_DFSR and is added to a replication set. DFS-R begins to replicate the contents of the SYSVOL_DFSR folders on all domain controllers. However, FRS continues to replicate the original SYSVOL folders and clients continue to use SYSVOL.
• 2 (redirected) The SYSVOL share, which originally refers to SYSVOL\domain\sysvol, is changed to refer to SYSVOL_DFSR\domain\sysvol. Clients now use the SYSVOL_DFSR folder to obtain logon scripts and Group Policy templates.
• 3 (eliminated) Replication of the old SYSVOL folder by FRS is stopped. The original SYSVOL folder is not deleted, however, so if you want to remove it entirely, you must do so manually.

You move your domain controllers through these stages by using the Dfsrmig.exe command. You use the following three options with Dfsrmig.exe:

• setglobalstate The setglobalstate option configures the current global DFSR migration state, which applies to all domain controllers. The state is specified by the state parameter, which is 0-3. Each domain controller is notified of the new DFSR migration state and migrates to that state automatically.
• getglobalstate The getglobalstate option reports the current global DFSR migration state.
• getmigrationstate The getmigrationstate option reports the current migration state of each domain controller. Because it might take time for domain controllers to be notified of the new global DFSR migration state, and because it might take even more time for a DC to make the changes required by that state, DCs are not synchronized with the global state instantly. The getmigrationstate option allows you to monitor the progress of DCs toward the current global DFSR migration state.

If there is a problem moving from one state to the next higher state, you can revert to previous states by using the setglobalstate option. However, after you have used the setglobalstate option to specify state 3 (eliminated), you cannot revert to earlier states.

Migrating SYSVOL Replication to DFS-R

To migrate SYSVOL replication from FRS to DFS-R, perform the following steps:

1. Open the Active Directory Domains And Trusts snap-in.
2. Right-click the domain and choose Raise Domain Functional Level.
3. If the Current Domain Functional Level box does not indicate Windows Server 2008 or Windows Server 2008 R2, choose either Windows Server 2008 or Windows Server 2008 R2 from the Select An Available Domain Functional Level list.
4. Click Raise. Click OK twice in response to the dialog boxes that appear.
5. Open an elevated Command Prompt.
6. Type dfsrmig /setglobalstate 1.
7. Type dfsrmig /getmigrationstate to query the progress of DCs toward the Prepared global state. Repeat this step until the state has been attained by all DCs.
   This can take 15 minutes to an hour or longer.
8. Type dfsrmig /setglobalstate 2.
9. Type dfsrmig /getmigrationstate to query the progress of DCs toward the Redirected global state. Repeat this step until the state has been attained by all DCs.
   This can take 15 minutes to an hour or longer.
10. Type dfsrmig /setglobalstate 3.
    After you begin migration from state 2 (redirected) to state 3 (eliminated), any changes made to the SYSVOL folder must be replicated manually to the SYSVOL_DFSR folder.
11. Type dfsrmig /getmigrationstate to query the progress of DCs toward the Eliminated global state. Repeat this step until the state has been attained by all DCs.
    This can take 15 minutes to an hour or longer.
    For more information about the Dfsrmig.exe command, type dfsrmig.exe /?.