upgrading AD 2003 to 2008R2

Hi,

     We have 2 domain controllers running Server 2003 SP1 that we'd like to upgrade to Windows Server 2008R2. I know how to do the upgrade for one domain controller but I'm not sure if it's as simple as just upgrading DC2 in the same way as DC1 or if something needs to be done to DC2 before upgrading DC1. Any insight on this would be appreciated!
Ted PezzulloVP Information TechnologyAsked:
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Will SzymkowskiSenior Solution ArchitectCommented:
however we aren't getting new servers we are upgrading the 2003 server to 2008R2 OS.
That being said what you will need to do is the following...
- Update your DHCP scopes for DNS to only DC1 (FSMO holder)
- Demote DC2 (secondary non FSMO holder)
- Format DC2 server install 2008R2
- Continue the steps from above for preparing the domain and forest
- promote DC2 to DC
- Transfer ALL fsmo roles to DC2 (set external time source link provided above)
- Update your DHCP clients to point to DC2 for DNS (you will also need to do this for your servers that have static DNS IP's)
- Demote your DC1 server
- Test replication etc  
- Format and install 2008R2 on DC1
- Promote DC1 as a DC
- update your DHCP scopes for DNS to point to DC1 and DC2
- You can keep the FSMO roles on DC2 if you like, it doesn't matter (typically rule of thumb is server with more resources CPU/MEMORY should hold the FSMO roles in a site)

POST Steps: Raise the functional level Domain/Forest to 2008R2
Configure DFS-R for Sysvol replication

Will.
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Will SzymkowskiSenior Solution ArchitectCommented:
The steps that need to be done are below...
- Ensure that replicaiton is working correctly (use the following commands)
-- repadmin /replsum
-- repadmin /showrepl
-- repadmin /showbridgeheads
-- DCDiag /v

Open in new window

- Make sure that the DFL and FFL are set to 2003 Native
- Prep the domain/forest using ADPrep32.exe (2003 servers that are 64bit use ADPrep.exe which is on the 2008R2 media)
- Install 2 Servers 2008R2
- Promote 1 server at a time as a DC
- Transfer the FSMO roles from 2003 DC to one of the 2008R2 DC's
- Set the external Time Source on the DC holding the PDC role
(configure time source: https://support.microsoft.com/en-us/kb/816042)
- Check Repliccation again using the above commands
- Update your DHCP clients to point to the new 2008R2 DC's for DNS
- Migrate any other roles on the DC to another server (DHCP etc.)
- Change all of your Static IP's on your servers for DNS to the new DC's 2008R2
- Demote each 2003 DC (1 at a time)
- Make sure that you wait for replication to complete before demoting the second 2003 DC

Note: make sure that you run the commands above before and after doing demoting or promoting.

Will.
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MAS (MVE)EE Solution GuideCommented:
You will have to run below command to install 2008 DC
adprep /forestprep
adprep /domainprep
adprep /domainprep /gpprep

https://technet.microsoft.com/en-us/library/dd464018(v=ws.10).aspx
https://www.petri.com/windows-server-2008-adprep
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Ted PezzulloVP Information TechnologyAuthor Commented:
Thank you Will Szymkowski, however we aren't getting new servers we are upgrading the 2003 server to 2008R2 OS.
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Seth SimmonsSr. Systems AdministratorCommented:
however we aren't getting new servers we are upgrading the 2003 server to 2008R2 OS

1)  if the 2003 servers are 32bit then you can't do an in-place upgrade as cross architecture upgrades (32bit to 64bit) are not supported
2) if the 2003 servers are 64bit you need to install SP2 first before a 2008 R2 in-place upgrade

don't recommend in-place upgrade but if you don't have any other choice...
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Ted PezzulloVP Information TechnologyAuthor Commented:
Thank you that is very helpful. I completely forgot to consider the 32 bit vs 64 bit issue. I checked all other specs except for that. So looks like we might need to purchase separate servers after all. Thank you Seth for pointing that out! Thanks Will for your thorough explanations.
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Will SzymkowskiSenior Solution ArchitectCommented:
other specs except for that. So looks like we might need to purchase separate servers after all. Thank you Seth for pointing that out! Thanks Will for your thorough explanations.

Although Seth is correct in regards to "IN-PLACE" upgrade the steps i have outlined for you in my second point mitigate this completely. You just have to rely on 1 DC during the transition.

Will.
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Ted PezzulloVP Information TechnologyAuthor Commented:
Will,

 If both of our 2003 AD servers are 32 bit, I'm not sure how we could upgrade to server 2008R2 since it is 64 bit without getting new 64 bit machines to migrate AD. Did I misunderstand what you were trying to say?
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Seth SimmonsSr. Systems AdministratorCommented:
as long as the hardware supports an x64 OS, you will be fine
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Will SzymkowskiSenior Solution ArchitectCommented:
Did I misunderstand what you were trying to say?

Yes you did. In my steps i outlined this is NOT an in-place upgrade. You have 2 DC's that are 2003 32-bit. So the only way to accomplish this USING THE SAME HARDWARE is demoting one DC first format and install the new OS, promote this DC transfer the roles, then perform the same steps on the other 2003 32-bit DC.

In my first comment i illustrated simply adding additional servers, but then you stated that you want to use the same hardware. You cannot do an in-place upgrade so i provided an alternative method to use the same hardware.

Will.
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