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SeemaKanwalGurmani-8582 avatar image
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SeemaKanwalGurmani-8582 asked DSPatrick answered

What happens to Windows Server 2012 Domain Controller when we Upgrade Domain & Forest Functional Level to Migrate to Windwos Server 2019

Dear Community,

I want to migrate Windows Server 2019 Active Directory Role to Windows Server 2019 Server. What happens to Windows Server 2012 Domain Controller when we upgrade Domain & Forest Functional Level to Windwos Server 2019 as its pre-requisite to upgarde to Widnwos Server 2019 Domain Controller.

Will my windows Server 2012 DC will keep running after I upgarde the Domain & Functional Level to 2012?


Kindly help me out in this regard.

windows-server-2019windows-server-2012
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DSPatrick avatar image
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DSPatrick answered

I'd just do them one at a time and confirm health is good in between doing them. Since you have multiple domain controllers you can take the old ones off line either before or after as needed. Having 2012 and 2019 domain controllers side by side long term is not a problem.

. --please don't forget to Accept as answer if the reply is helpful--






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DSPatrick avatar image
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DSPatrick answered

2012 domain controllers will be fine.

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2019, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can decommission / demote old one.


--please don't forget to Accept as answer if the reply is helpful--










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FanFan-MSFT avatar image
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FanFan-MSFT answered SeemaKanwalGurmani-8582 commented

Hi,
For your questions:
If you want to keep your 2012 DCs in the domain, the function level can't be raised to 2016.
If you want to raise the function level to 2016 , the 2012 DCs must be demoted (after the new DC was added) .

To add the 2019 DCS:

The minimum requirements to add a Windows Server 2019 Domain Controller is a Windows Server 2008 functional level. The domain also has to use DFS-R as the engine to replicate SYSVOL.

Since you have 2012 DCs in the domain, make sure the fonctional is 2012 (or raise it to 2012 ), and confirm the DFSR is used for the sysvol replicaiton.
You can confirm the DFSR is used by the command dfsrmig.exe /getglobalstate
If the Result: 3 (ELIMINATED) the DFSR is used for the replication.
If not, FRS should be migrated to DFSR:
https://docs.microsoft.com/en-us/windows-server/storage/dfs-replication/migrate-sysvol-to-dfsr

After the 2 requirements meet, , we should also make sure everything is working well, following command for your reference :
Dcdiag /v >c:\dcdiag1.log
Repadmin /showrepl >C:\repl.txt
Repadmin /showreps * 

Then the new DC can be added , following for your reference:
https://www.petenetlive.com/KB/Article/0001262(third-party link)

Last, you can consider to keep the old DC or raise the functional level.

This response contains a third-party link. We provide this link for easy reference. Microsoft cannot guarantee the validity of any information and content in this link.

Best Regards,

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Dear FanFan-MSFT,

I will eventually migrate all DCs from 2012 to 2019. But I am asking about the time when it's in progress. Like when I upgrade the Functional Level to 2012, what happens to 2012 DCs? Will they stop working at that time?
Also I want to ask that after upgrading the functional level and setting DFSR to be used for the sysvol replicaiton, Will my 2012 DCs will still be functional.At this time of course I would have yet added 2019 DC?
But ofcourse After adding 2019 DC my 2012 DC would ahve to be demoted. Thats my understanding.
Please correct me If I am wrong.But also do tell me will it become non-functional on its own?

Thanks.

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DSPatrick avatar image
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DSPatrick answered SeemaKanwalGurmani-8582 commented

what happens to 2012 DCs?

nothing

Will they stop working at that time?

No

want to ask that after upgrading the functional level and setting DFSR to be used for the sysvol replicaiton, Will my 2012 DCs will still be functional.

Yes, see my reply above. --please don't forget to Accept as answer if the reply is helpful--











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Hello DSpatrick,

One more thing I want to ask that which type of migration I should go for? There are three types of migrations I can see in the link that you shared:

ttps://techcommunity.microsoft.com/t5/storage-at-microsoft/streamlined-migration-of-frs-to-dfsr-sysvol/ba-p/425405
1. Quick Migration (where you don’t know if your domain controllers are healthy, and you want a rollback option)
2. Express Migration (where you are sure that your domain controllers are healthy, and you want a rollback option)
3. Hyper Migration (where you want to migrate with the minimum steps and are confident of domain controller health)
Which type of Migration should I use?
Also let's say I first migrate my domain controller on window server 2019 on one site which has all FSMO roles.
and then I migrate DC on each site on each coming day and not like demote all widnwos server DCs at the same time to keep everything going smoothly so can i do that?







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SeemaKanwalGurmani-8582 avatar image
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SeemaKanwalGurmani-8582 answered SeemaKanwalGurmani-8582 commented

That's great. One more thing that I want to ask is that once I want to add additional domain controller with Windows Server 2019 , at this stage what will happen to Windows Server 2012?I mean can I keep migrating each 2012 after that or will I have to decomission 2012 as you said:

"when all is good you can decommission / demote old one."

So I have like 4 Domain Controllers one on each site all with Windows Server 2012. So how will I migrate each DC to Windows Server 2019 and what about demoting them?
Like please guide on this.

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My second question is that will window server 2012 on other site and windwos server 2019 keep on replicating information eventhough FRS replication ahs been upgraded to DFSR?
Also after upgrading DFSR and adding 2019 DCs you said my 2012 DC wtill stay functional. Infact you said I can run both DCs 2012 and 2019 along side? So my question is that Then why do I need to upgrade 2012 DCs If they will keep running?
I know my last question sounds weird but I really wanted to ask you this question?

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DSPatrick avatar image
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DSPatrick answered

will window server 2012 on other site and windwos server 2019 keep on replicating information eventhough FRS replication ahs been upgraded to DFSR?

Active directory replication is per domain. When you migrate FRS->DFSR all domain controllers for the domain are a part of the migration. Yes Server 2003 R2 and higher can use DFSR








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