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Using the Active Directory Migration Tool in a large environment

Discover why using the Active Directory Migration Tool in a large Exchange Server environment may not be the best option for a successful migration.

I am adding a child domain to an existing large single domain with multiple Exchange servers. (We are adding the child domain for local administrative reasons). The email server for this location is Exchange 5.5. It has an Active Directory Connector (ADC) on it now, and we will be upgrading it to Exchange Server 2003. We will be doing so via a new server with a clean install, and then moving resources over.

I believe the best way to proceed is as follows:

  1. Create the domain controller (DC) for the new child domain.
  2. Add the new Exchange server to the child domain.
  3. Use the Active Directory Migration Tool (ADMT) to move resources.
  4. Move mailboxes using ExMerge.
  5. 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?

Microsoft tackles a related issue in its article, " Addressing problems that are created when you enable ADC-generated accounts."

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.

Do you have comments on this Ask the Expert Q&A? Let us know.

Related information from SearchExchange.com:

  • Expert Advice: Move accounts from Exchange 5.5 to Exchange 2003
  • Learning Center: The Exchange Server and Active Directory Toolbox
  • 11 tips in 11 minutes: Migrating from Exchange Server 5.5 to 2003
  • Reference Center: Exchange Server deployment and migration advice
  • Dig Deeper on Exchange Server setup and troubleshooting