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Downgrading a DFS Server without losing data?

Posted on 2015-01-12
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Last Modified: 2015-03-16
We have been trying for a long period to resolve issues using Server 2012 DFS servers; and have finally decided to roll back to Server 2008 R2 instead.  There are 2 machines in the DFS setup, one of which has been completely wiped (data and OS) and rebuilt.  the other machine is a 2012 Server which is currently the master server in the DFS Namespace, which is still in use.

The plan now, is to finish rebuilding the second server with 2008 R2, and use Robocopy to transfer the data across from the life server, share by share, then add the server into the DFS Replication and namespace.  Once it has finished replication setup between the two servers, change the new server to be the master, and disable the current primary server in DFS-N and replication.

From here i'm a little unsure of the best step - would i be better completely wiping the second server as well and doing a full data transfer, or is there a way i can still use the data on the current 2012 server by restarting the replication once i have rebuilt it in 2008 R2?  As this is a live environment my primary concern is to NOT lose any data (obviously!)
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Question by:Amaze_IT
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Expert Comment

by:Mahesh
ID: 40544919
Approach One:
Ensure that all drive letters are same on 2012 and 2008 R2 servers
Use robocopy to copy data to 2008 R2 server and create shares as is, probably you can export shares registry on 2012 server and import it on 2008 R2 to build shares
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Shares]

Export DFS configuration on source 2012 server
http://blogs.technet.com/b/askds/archive/2008/01/15/migrating-your-dfs-namespaces-in-three-sorta-easy-steps.aspx
Then remove DFS replica and name space on 2012 server
Ensure it is got removed from AD, force AD replication
Import DFS configuration on 2008 R2 servers
Build new DFS replicas

2nd option:
DFSN and DFSR in 2012 and 2008R2 are compatible (as long as you have your namespaces configured for 2008-mode)
Add 2008 R2 as name space server and remove name space from 2012

3rd option:
Last option I highly recommend is to introduce 2012 R2 servers in existing 2012 DFS servers and migrate DFS to 2012 R2

I don't know what exact issues you are facing on 2012 servers, but I still suggest you to go with 2012 R2
DFS database autorecovery is disabled on 2012 in case of hard reboot
However it is again enabled on 2012 R2 and I am not aware with any major issues with 2012 R2
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by:Amaze_IT
ID: 40548590
Thanks for the comprehensive information!

The reason we are thinking of rolling back to 2008 R2 is because of a number of reasons!

Firstly, the plan was to have 2 DFS servers, one at each of our main sites, which would allow local resource access for users.  This required us to use PeerLock to prevent people opening the same files on different sites.  

Secondly, we found that Mac users could not reliably access DFS shares through SMB, and even when accessing shares directly using SMB1 we had massive problems with users opening Adobe CS files and browsing directories.  To try and remedy this, we employed ExtremeZ-IP - which unfortunately does not function with DFS properly (IT "...simulates DFS..." (quote)) - additionally, the way EZ-IP works, it does not show up under the normal MS File Sharing, and so is not detected by Peerlock, meaning that file locking fails to function for mac users.

For this reason, we resorted back to a single server with a DR replication server at our other site.  This then presented us with another issue - very poor data transfer rates from the remote office.  This office is running a 100MB direct link (1 hop, 14ms latency) and doesn't normally experience issues.  However, using Server 2012, the link speed was running between 2MB/s and 200KB/s and fluctuating wildly, meaning large files took forever to load at all.  this problem improved when using Server 2008 R2 (We did try all the usual fixes and registry changes first but with no success).  Hence why we were thinking of rolling back to Server 2008 R2 across all servers!
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Expert Comment

by:Mahesh
ID: 40548615
Thanks for insights
No matter which version of DFS you use, if both sides are active, you do require peerlock

Still I think  you can switch over to 2012 R2 instead of 2008 R2
Also if you could keep file access locally only at both locations and establish replica between each other
No need to publish replica as name space and if you want to publish, keep remote target disabled so that  user will get connected to local target only
By default DFS will try to connect to targets in same site as DFS is AD site aware application.
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Author Comment

by:Amaze_IT
ID: 40548664
thanks for the advice.  unfortunately, that is what we were attempting to do, but due to having to use ExtremeZ-IP for Mac users to be able to connect to the shares, PeerLock does not detect them accessing data and lock the remote copy of the files; meaning that it can be opened at both locations locally - causing obvious issues!
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Author Comment

by:Amaze_IT
ID: 40563951
Om so to update on this - i have decided to take the advice on board and we have rebuilt the secondary server as a 2012 R2 Server instead!

However, i've run into what i think may well be a problem - due to the way the old server (the one i've just rebuilt) came out of the DFS replication, the server still exists in the replication group (although replication has been disabled on all shares etc).  Firstly - am i safe to just delete this replication member from the whole group now without any problems?

Secondly - and this is what i am worried about - when DFS replication was set up, all the replicated folders are in one Replication group "DFS" as opposed to each replicated folder having it's own group. The plan was to robocopy each share over at a time, then add the new server into the replication for that share, let it sort itself out, then change the new 2012 R2 server to be the primary server (there is far too much data to do this as a "one shot" copy so has to be done in stages overnight).  However, is this possible with just one group - if i add a new member will it not just add it to every folder straight away and try to start replicating?  How easy is it to change the primary member over to the new server once the new replica folder is live, and is there any way i can confirm this has been completed?
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Mahesh earned 500 total points
ID: 40564722
You can delete member from replication group, however deleted server will remain in DFS database as tombstone object for next 60 days
So once you removed server, do not add it again.
Deleting member will not delete data on any member
After removal if you delete any data from that deleted member and again added to same Replication group, then DFS will replicate deletion to other members causing data loss
Hence do not add that member again

Even if all DFS shares are in same replication group, I don't see any problem, the purpose of multiple replication group is to define replication schedule
Even if you add new member, you do need to specify target path of replication for each folder

Imp Note:
Once you added new 2012 R2 server as DFS replica member for all replicated folders, wait until that server finishes initial sync
U will see DFSR event 4104 which tells you that initial sync is completed
After that both servers will start data replication and you can manually check replication from DFS management tool \ connection object
Once both servers started replicating correctly, then you can change primary member

The DFS Management tool doesn't allow you to set the Primary Member of a replication group. You either need to use DfsrAdmin.exe command line or PowerShell some thing like below
Set-DfsrMembership -GroupName "rg01" -FolderName "rf01" -ComputerName srv01 -ContentPath c:\rf01 –PrimaryMember $true

Open in new window

http://blogs.technet.com/b/filecab/archive/2013/08/20/dfs-replication-in-windows-server-2012-r2-if-you-only-knew-the-power-of-the-dark-shell.aspx
The command need to be run for each replicated folder I guess.
After that Wait for a DFS Replication Event 4112 in the DFS Replication Event Log on new primary member, which indicates that the replication folder initialized successfully as primary
Then force AD replication and Then run dfsrdiag pollad on both DFSR servers
Check below article
http://blogs.technet.com/b/filecab/archive/2013/08/21/dfs-replication-initial-sync-in-windows-server-2012-r2-attack-of-the-clones.aspx

Then you can run below command to find out DFSR primary member
Get-DfsrMembership -GroupName * -ComputerName *

Open in new window

https://technet.microsoft.com/en-us/library/dn296589.aspx

Check below article to prestige data with robocopy
https://technet.microsoft.com/en-us/library/dn495044.aspx

Take data backup once before you change primary member
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