Tag Archives: FRS

What is Content Freshness protection in DFSR?

Healthy Replication is a must for active directory environment. SYSVOL folder in domain controllers contain policies and log on scripts. It is replicated between domain controllers to maintain up to date config (consistency). Before windows server 2008, it used FRS (File Replication Service) to replicate sysvol content among domain controllers. With Windows server 2008 FRS was deprecated and introduced Distributed File System (DFS) for replication.

A healthy replication required healthy communication between domain controllers. sometime the communication can interrupt due to domain controller failure or link failure. Based on the impact it is still possible that the communication re-established after period of time. Then it will try to resume replication and catch up with SYSVOL changes. In such scenario, we may see event 4012 in event viewer. 

The DFS Replication service stopped replication on the replicated folder at local path c:\xxx. It has been disconnected from other partners for 70 days, which is longer than the MaxOfflineTimeInDays parameter. Because of this, DFS Replication considers this data to be stale, and will replace it with data from other members of the replication group during the next replication. DFS Replication will move the stale files to the local Conflict folder. No user action is required.

With windows server 2008, Microsoft introduced a setting called content freshness protection to protect DFS shares from stale data. DFS also use a multi-master database similar to active directory. It also has tombstone time limit similar to Active Directory. The default value for this is 60 days. If there were no replication more than that time and resume replication in later time, it can have stale data. It is similar to lingering objects in AD. To protect from this, we can define value for MaxOfflineTimeInDays. if the number of days from last successful DFS replication is larger than MaxOfflineTimeInDays it will prevent the replication. 

We can review this value by running,

For /f %m IN ('dsquery server -o rdn') do @echo %m && @wmic /node:"%m" /namespace:\\root\microsoftdfs path DfsrMachineConfig get MaxOfflineTimeInDays

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There is two ways to recover from this. First method is to increase the value of MaxOfflineTimeInDays. it can be done using,

wmic.exe /namespace:\\root\microsoftdfs path DfsrMachineConfig set MaxOfflineTimeInDays=120

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It is recommended to run this on all domain controllers to maintain same config. 

If you not willing to change this value, it still can recover using non-authoritative restore. It will remove all conflicting values and take an updated copy. 

I have already written an article about non-authoritative restore of SYSVOL and it can be find in http://www.rebeladmin.com/2017/08/non-authoritative-authoritative-sysvol-restore-dfs-replication/ 

This is not only for SYSVOL replication. It is valid for DFS replication in general. 

Hope this was useful and if you have any questions feel free to contact me on rebeladm@live.com also follow me on twitter @rebeladm to get updates about new blog posts.

Step-by-Step Guide for upgrading SYSVOL replication to DFSR (Distributed File System Replication)

SYSVOL is a folder shared by domain controller to hold its logon scripts, group policies and other items related to AD. All the domain controllers in network will replicate the content of SYSVOL folder. The default path for SYSVOL folder is %SystemRoot%\SYSVOL. This folder path can define when you install the active directory.

Windows Server 2003 and 2003 R2 uses File Replication Service (FRS) to replicate SYSVOL folder content to other domain controllers. But Windows server 2008 and later uses Distributed File System (DFS) for the replication.  DFS is more efficient than FRS. Since windows server 2003 is going out of support, most people already done or still looking for migrate in to latest versions. However migrating FSMO roles WILL NOT migrate SYSVOL replication from FRS to DFS. Most of the engineers forget about this step when they migrate from windows 2003 to new versions.

For FRS to DFS migration we uses the Dfsrmig.exe utility. More info about it available on https://technet.microsoft.com/en-au/library/dd641227(v=ws.10).aspx

For the demo I am using windows server 2012 R2 server and I migrated FSMO roles already from a windows server 2003 R2 server.

In order to proceed with the migration forest function level must set to windows server 2008 or later. So if your organization not done this yet first step is to get the forest and domain function level updated.

You can verify if the system uses the FRS using dfsrmig /getglobalstate , To do this

1)    Log in to domain controller as Domain admin or Enterprise Admin
2)    Launch powershell console and type dfsrmig /getglobalstate. Output explains it’s not initiated DFRS migration yet.

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Before move in to the configurations we need to look into stages of the migration.

There are four stable states going along with the four migration phases.

1)    State 0 – Start
2)    State 1 – Prepared
3)    State 2 – Redirected
4)    State 3 – Eliminated

State 0 – Start

With initiating this state, FRS will replicate SYSVOL folder among the domain controllers. It is important to have up to date copy of SYSVOL before begins the migration process to avoid any conflicts.

State 1 – Prepared

In this state while FRS continues replicating SYSVOL folder, DFSR will replicate a copy of SYSVOL folder. It will be located in %SystemRoot%\SYSVOL_DFRS by default. But this SYSVOL will not response for any other domain controller service requests.

State 2 – Redirected

In this state the DFSR copy of SYSVOL starts to response for SYSVOL service requests. FRS will continue the replication of its own SYSVOL copy but will not involve with production SYSVOL replication.

State 3 – Eliminated

In this state, DFS Replication will continue its replication and servicing SYSVOL requests. Windows will delete original SYSVOL folder users by FRS replication and stop the FRS replication.

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

Let’s look in to the migration steps.

Prepared State

1.    Log in to domain controller as Domain admin or Enterprise Admin
2.    Launch powershell console
3.    Type dfsrmig /setglobalstate 1 and press enter

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4.    Type dfsrmig /getmigrationstate to confirm all domain controllers have reached prepared state

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Redirected State

1.    Log in to domain controller as Domain admin or Enterprise Admin
2.    Launch powershell console
3.    Type dfsrmig /setglobalstate 2 and press enter

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4.    Type dfsrmig /getmigrationstate to confirm all domain controllers have reached redirected state

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Eliminated State

1.    Log in to domain controller as Domain admin or Enterprise Admin
2.    Launch powershell console
3.    Type dfsrmig /setglobalstate 3 and press enter

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4.    Type dfsrmig /getmigrationstate to confirm all domain controllers have reached eliminated state

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This completes the migration process and to confirm the SYSVOL share, type net share command and enter.

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Also make sure in each domain controller FRS service is stopped and disabled.

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If you have any question regarding the post feel free to email me at rebeladm@live.com