Hello,Now I use 2 hardware computers for Exchange:1. Windows 2000 Std Srv AD DC / Exchange 2000 Std Srv2. Windows 2003 Std Srv / Exchange 2003 Std SrvI already migrated almost all mailboxes from N1 to N2. I plan to remove that too old N1 and let it be just a file server. I want to migrate all other roles from it to a new Windows 2008 Std Srv / Exchange 2007 Std Srv and continue using N2 also. It means the new one should be the only AD DC.Is it possible?

Hi,If I understood correctly, you want to install Exchange 2007 SP1 on Windows 2008 and this server is also a Domain Controller. Actually it is supported but NOT recommended to install Exchange on a DC due to security, performance & recovery prospective and a member server is preferred.Check out "Installing Exchange 2007 on Directory Servers" session in -http://technet.microsoft.com/en-us/library/aa996719.aspxYes of course coexistence of Exchange 2003 & Exchange 2007 is possible. Here is a good start to understand it.Planning for Coexistencehttp://technet.microsoft.com/en-us/library/aa998186.aspxAmit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

I know it's not the best idea to install exchange on an AD DC server and I know Exchange 2003 and Exchange 2007 can coexist. However, I see the problem in migrating that N1 with all of its roles to a new box (Windows 2008 / Exchange 2007) and my main question is if it's possible. Don't forget that N1 and N2 now coexist just fine.If the migration is possible is there any risk for that N2 also after the migration?

It is possible, but not recommend as Amit said. It will require extending forest schema for new DC (Windows Server 2008) and migrating the roles properly After the migration, please change the preferred DNS on N2 from old DC to the new one if new DC is also a DNS server

You mean as I once extended that schema of Windows 2000 AD DC to Windows 2003 schema when I added N2 server? It was not a problem. I remember some error occured when updating the AD Connector but everything seemed OK since that migration and successfully migrated the mailboxes to that new N2. Is it a good idea to migrate all roles from N1 to N2 first making N2the AD DC and then add that new box as then N1 won't be important as it would be just a member file server?

N2 is already Exchange 2003 server, right? This might make things more clear...."You can run Exchange Server 2003 on either a member server or on a domain controller. After you install Exchange Server 2003 on a server, do not change the role of the server. For example, if you install Exchange Server 2003 on a member server, do not use the Dcpromo tool to promote the server to a domain controller. Or, if you install Exchange Server 2003 on a domain controller, do not use the Dcpromo tool to demote the server to a member server. Changing the role of a server after you install Exchange Server 2003 may result in loss of some Exchange functionality and is not supported." -http://support.microsoft.com/kb/822179Amit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

Yes, it is. I wrote it in the firs post already. Now I understand I can not change that N2 member server to an AD DC. So, it's not an option. I think the only option is:1. Upgrade the schema of N1(and maybe N2?) to a Windows 2008 schema; 2. Install the new box(Windows 2008); 3. Promote it as an AD DC;4. Migrate N1 to that new box;5. Remove the roles of N1.Am I right? If so, the main problem would be "4. Migrate N1 to that new box." ofcourse.

Hello,You can follow below steps for your Point 4 as detailed.- You need to uninstall Exchange 2000 from N1 before running DCPromo to demote DC. You mentioned that all mailboxes have been moved from N1 to N2 and I assume that it is the first Exchange 2000 server in that admin group. You need to follow below article to move PFs.How to remove the first Exchange 2000 Server computer from the sitehttp://support.microsoft.com/kb/307917- Migrate other windows related roles to New box (Windows 2008). However we are not the best resources to give suggestions/recommendations on Windows migration. You may consult in Windows forum to get better responses (This is Exchange Server - Deploy forum so visit of Windows experts would be less.)Windows Forum:http://social.technet.microsoft.com/Forums/en-US/category/windowsserver/- Install Exchange 2007 on new box.- Move the mailboxes and PFsas per your requirement from N2 to this new box to run Exchange 2007 in coexistence.Amit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

Yes, you may get the solution more efficiently from windows forum Per my knowledge, as migration part, once the new windows 2008 server has been promoted to additional DC and synced all AD data, we shall transfer roles to the new one, also the DNS, DHCP and WINS if necessary. For DNS, it will set up properly after DNS service is installed on new DC; for DHCP and WINS, the data need to be exported from old DC and imported to the new References: How to move a DHCP database from a computer that is running Windows NT Server 4.0, Windows 2000, or Windows Server 2003 to a computer that is running Windows Server 2003 A relevant thread