Migration Guide: FRS to DFS Replication

In an effort to reduce SYSVOL bloat and replication across Domain Controllers (DCs) consider using DFS Replication (DFSR). A bigger reason however is that FRS is no longer supported in Server 2012, so if you plan to upgrade DCs to Server 2012 – then you must do this first. Want a third reason? If you are using Read Only DCs (RODCs) and are still on FRS it is easy for the SYSVOL on the RODC to become out of synch with other DCs; better still in Server 2008 R2 and above DFS-R ensures that the RODC SYSVOL can never be modifed.

DFS-R simply provides better and more efficient synchronisation than the old world File Replication Service (FRS). Prior to proceeding you may want to indeed check  and make sure that you are not already using DFS-R. Jump into a command prompt and type in this command:

Dfsrmig /GetGlobalState

If the output is shown as “Current DFSR global state: ‘Eliminated’” then you are already using DFS-R and there is no need to go any further. Stop right here.

dfsrmig command

dfsrmig command

Did You Know: the DFS-R migration process actually uses Robocopy (yes! Robocopy) to copy the SYSVOL data at various stages


All Domain Controllers need to be online and available. If you have any redundant DCs listed and they have not been cleaned up (meta data an’ all!) then do so before starting this task

Depending on what Server OS and Service Pack Level you are on ALL DCs may need to be located in the default Domain Controllers OU. If they are located in a sub OU or elsewhere (for policy reasons usually) then consider moving them into the default location temporarily during the migration

The PDC Emulator MUST be online during the whole process – that’s the dude with the most up to date Policy and it is the DC that this whole process talks to the most

You need at least a Windows 2008 Functional Level for your Domain, so get rid of those soon to be end of life Server 2003 R2 DCs first

4 Steps to DFS-R

There are 4 steps to migrate from FRS to DFS-R using the Dfsrmig command:

  1. Health Check: Run the following commands to check the health of current replication
    1. Ensure there is enough free disk space on each Domain Controller for the migration
    2. Run repadmin /replsummary to ensure current replication is healthy, resolve any issues
    3. Run repadmin /showrepl * /csv > replication.txt to ensure current replication is healthy, resolve any issues in the output file
  2. Migrate to Prepared State: Use the command Dfsrmig /SetGlobalState 1 to begin the migration, use Dfsrmig /GetMigrationState to check the current status of this step. Do NOT proceed until this step is complete
  3. Migrate to Redirected State: Use the command Dfsrmig /SetGlobalState 2 for this second step, use Dfsrmig /GetMigrationState to check the current status of this step. Do NOT proceed until this step is complete. If you wish to stay with FRS for SYSVOL replication then stop here.
  4. Migrate to Eliminated State: [NOTE: There is no going back after this step! You have been warned] Use the command Dfsrmig /SetGlobalState 3 for this final step, use Dfsrmig /GetMigrationState to check the current status of this step. Once this step is complete so is the migration.

That’s all there is too it. Honest.

If you did execute Step 4 in error, then as I said there is no going back. Ever. Except of course unless you rebuild the whole domain (a whole lot of fun for you then!).

Clean Up Tasks – get rid of FRS!

Now that you have succesfully migrated to DFS-R you now need to

  • Delete the old SYSVOL directory
  • Disable and then Remove the NTFRS Service

You really should download and read the full Microsoft guide found here: http://technet.microsoft.com/en-us/library/dd640019(WS.10).aspx

As usual, get in touch if you have any questions.

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  1. Excellent article very helpful thank you so much. Love reading your blog now I need to start updating mines regularly