I believe the best way to proceed is as follows:
- Create the domain controller (DC) for the new child domain.
- Add the new Exchange server to the child domain.
- Use the Active Directory Migration Tool (ADMT) to move resources.
- Move mailboxes using ExMerge.
- Move the other resources over.
In creating the child domain, I will be moving existing resources, user accounts, client PCs and servers over using the ADMT. When I move the accounts over, will the email information be updated? If not, what is the best way to accomplish the move?
As another option, should I add the new Exchange server now, before we add the child domain, move the resources over from the old Exchange 5.5 server, and then migrate to the new DC?
You should definitely consider testing this process in a lab environment. This combination may be completely fine for a small environment, but more difficult in the medium to large enterprise.
After looking at ADMT 3.0, the following points would cause me to consider using a third-party tool in a larger environment:
- ADMT supports only a limited set of Active Directory configurations.
- The tool migrates a limited set of Active Directory data.
- It cannot synchronize directories. Because migrations can last a while, your originally migrated data may become obsolete and need to be updated.
- ADMT updates only limited types of resources.
- It does not provide statistics information on the Exchange migration project. You may need detailed statistics on your migration activities.
- It does not provide rollback functionality in case of mistakes. I don't believe ADMT allows you to roll back resource updating tasks, and the Active Directory migration may be restricted to the last session only. Also, account merging cannot be undone.
Overall, your Exchange migration in a small environment, with careful planning and testing, should be successful. However, I want you to go into the situation with your eyes wide open. It might be easier to engage a technology outsourcer or software vendor that specializes in Exchange migrations.
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