When a company with an existing Exchange Server organization begins adding Exchange 2007 servers to the mix, it is tempting to remove the old Exchange 2003 servers immediately upon completion of the migration process. However, it has been my experience that immediately decommissioning legacy servers is a big mistake. In this article, I will explain why this is the case, and what you need to do to gracefully remove legacy mailbox servers after a migration.
If you have recently deployed an Exchange 2007 mailbox server, and migrated all of the mailboxes from an Exchange 2003 server to it, you’re probably ready to decommission the legacy server. Even so, I would advise waiting for at least two weeks before you pull the plug on Exchange 2003. The reason why I say this is that if your users are using Outlook then their Outlook profiles are currently going to be directed to the old Exchange 2003 mailbox server. As the users begin to log on for the first time after the migration, Outlook should realize that mailboxes have been moved, and redirect each user’s profile to the new mailbox location.
If you remove the old mailbox server before users have had a chance to log onto the new server, then there’s a good chance that Outlook will not be able to automatically redirect the users profile to the new mailbox location. Waiting at least two weeks to pull the plug on the old mailbox server ensures that even users who are currently on vacation have a chance to log on, and have their profiles redirected before you decommission the old server.
The Decommissioning Process
Contrary to what I have read on a couple of websites, decommissioning and old mailbox server (or any Exchange Server for that matter) involves more than just shutting the server down and unplugging it. That’s because the majority of Exchange Server’s configuration information is stored in the Active Directory. Even if an old server has been taken off-line, the references to the server remain in the Active Directory and the rest of the Exchange Server organization assumes that the legacy server is still a part of the organization. This can lead to some rather nasty side effects, such as messages backing up in queues to nowhere.
Properly decommissioning an old mailbox server involved three primary steps:
- You must remove all routing group connectors from the server.
- You must uninstall Exchange from the server.
- You must remove the appropriate routing groups from the Exchange Server organization.
I want to spend the remainder of this article focusing on routing groups and routing group connectors. Before I do though, I just want to mention that step number two requires you to uninstall Exchange Server. Before you can do that, you must have removed all mailboxes and public folders from the server. For the purposes of this article, I am assuming that you have done this as a part of the migration process.
Routing Group Connectors
As you have probably heard, Exchange Server 2007 does not use routing groups, and therefore routing group connectors are not even necessary in organizations running solely on Exchange Server 2007. The first part of the decommissioning process involves removing the routing group connectors from the server that you’re decommissioning. I will walk through the process in a step-by-step manner in part two of this series. For now though, I wanted to mention that you have to be careful about which routing group connectors you remove.
The catch is that you cannot indiscriminately delete routing group connectors. If a routing group connector serves as the only link between two routing groups or if it served as the only link between Exchange Server 2003 and Exchange Server 2007, and you delete it, then communications between routing groups will cease to function.
In order to prevent this from happening, you need to construct a topology diagram of your Exchange Server organization, and figure out the specific purpose of each routing group connector. By doing so, you can figure out which routing group connectors can be safely removed, and which ones would have serious consequences if you remove them.
If you do determine that you cannot remove a routing group connector without causing problems, then you need to create a routing group connector on a separate server. This routing group connector should serve the same purpose as the one that you are about to delete. Once you have an alternate connector in place, you can safely remove the routing group connector from the legacy Exchange server.
In this article, I have begun talking about the process for decommissioning a legacy Exchange Server. In part two of this article series, I will continue the discussion by showing you how to remove routing groups and routing group connectors.
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