AD Modernization Project : Part 2 - FRS to DFSR transition

The second part of the AD modernization project will be transition from File Replication Service (FRS) to Distributed File System Replication (DFS-R).

The FRS was used for replicating the contents of the sysvol folder (which saves all of the GPO's in the enterprise) between domain controllers in Windows Server 2000 and Windows Server 2003. Windows Server 2008 or later active directory uses DFSR for replication of SYSVOL share. Any Active directory environment built with Windows Server 2008 or later will use DFSR by default.

Active Directory Environment that were upgraded from Windows Server 2000/2003 will require a process to transition SYSVOL replication from FRS to DFSR.

Prerequisites -

1. Forest functional level must be set to Windows server 2008 or later.
2. Healthy active directory services.
3.  Active directory replication between domain controllers must be operational.
4. It is required to do the migration on PDC emulator as it is the authority on SYSVOL.

Migration States - 

There are four states in the migration process. Each stage needs to be reached by all of DC before proceeding to the next. These states are:

·       Start - State 0 

In this state, FRS will replicate the SYSVOL folder among all domain controllers. It is very important to have up to date SYSVOL folder before migration.

·       Prepared - State 1

In this state, FRS continues replicating SYSVOL folder. DFSR will also replicate a copy of SYSVOL folder and it will be in %SystemRoot%\SYSVOL_DFRS by default. But SYSVOL folder will not respond for any other domain controller service request.

·       Redirected - State 2

In this state, DFSR copy of SYSVOL starts to response for any other domain controller service request. FRS will continue the replication of its own copy SYSVOL but will not involve with production replication.

·       Eliminated  - State 3

In this state, windows will delete the original SYSVOL folder by FRS and stop the FRS replication. DFSR will continue replication process and will response for any domain controller service request.

Note-In order to migrate from FRS to DFSR, its must to go from State 1 to State 3.

Below is the migration process -

The following steps detail the process end to end. Before each step, DC replication will need to be verified. Proceed only if replication is working as expected.

Repadmin /showrepl command will show the replication status. 

Before start running the above commands the current state can be verified to see if the system is still running FRS by the following command –

Dfsrmig.exe /getglobalstate – This will provide the information of the current state if the migration has not been started yet a message appears like “DFSR migration has not yet initialized. To start migration please set global state to desired volume.”

Prepared State

·       Login to the domain controller as Domain Admin or Enterprise Admin.

·       Open Powershell console.

·       Type dfsrmig /setglobalstate 1 and press Enter.

·       Type dfsrmig /getmigrationstate to confirm.

Dfsrmig.exe /getglobalstate can be used to check the current state, The current state of all the domain controller should be in “Prepared” state and a message should be shown as “All Domain Controllers have migrated successfully to Global state (‘Prepared’). Migration has reached a consistent state on all Domain Controllers.”

Redirected State

·       Login to the domain controller as Domain Admin or Enterprise Admin.

·       Open Powershell console.

·       Type dfsrmig /setglobalstate 2 and press Enter.

·       Type dfsrmig /getmigrationstate to confirm.

Dfsrmig.exe /getglobalstate can be used to check the current state, The current state of all the domain controller should be in “Redirected” state and a message should be shown as “All Domain Controllers have migrated successfully to Global state (‘Redirected’). Migration has reached a consistent state on all Domain Controllers.”

Eliminated State

·       Login to the domain controller as Domain Admin or Enterprise Admin.

·       Open Powershell console.

·       Type dfsrmig /setglobalstate 3 and press Enter.

·       Type dfsrmig /getmigrationstate to confirm.

              

Now migration process is completed. Dfsrmig.exe /getglobalstate can be used to check the current state, The current state of all the domain controller should be in “Eliminated” state and a message should be shown as “All Domain Controllers have migrated successfully to Global state (‘Eliminated’). Migration has reached a consistent state on all Domain Controllers.”

To confirm the SYSVOL Share, type net share and press Enter. Also make sure that FRS service is Stopped and Disabled.