Upgrading to Exchange Server 2007

Deploying Microsoft Exchange Server 2007 requires careful planning. If you're bringing Exchange 2007 into an organization with Exchange Server 2003 or Exchange 2000 Server, you can't just insert the installation disk into one of your existing Exchange servers and run the Exchange Server 2007 Setup wizard. Here's what you'll need to do to make sure your legacy organization is ready to receive the upgrade.

Before You Begin
Exchange 2007 runs only on 64-bit versions of Windows Server 2003. In contrast, Exchange 2003 runs only on 32bit Windows Server OSs. Therefore, an in-place upgrade is impossible. If you want to bring Exchange 2007 into an Exchange 2003 organization, you'll have to perform a migration, which means installing 64-bit Windows 2003 on a new server, installing Exchange 2007, transferring data from an Exchange 2003 server, and then decommissioning the old server if necessary.

You probably have a lot of money invested in the hardware that's currently running Exchange 2003. Assuming that your old servers meet the minimum recommended hardware requirements for running Exchange 2007—for example, they have processors that will work with both 32-bit and 64-bit OSs—you might be able to reuse them. For example, you could migrate the contents of one of your existing servers to a new Exchange 2007 server. When that migration is complete and has been thoroughly tested, you can reformat the old server, install 64-bit Windows 2003 on it, then install Exchange 2007. You could then migrate the contents of another server to this server, and so on, in a leapfrog approach to upgrading. In some instances, you might be able to get away with having to purchase only one new server.

Initial AD Preparation
Every version of Exchange Server since Exchange 2000 has been dependent on Active Directory (AD) for storing information about the organization. Exchange 2007 is no exception, so you'll need to adequately prepare your AD prior to installing the first Exchange 2007 server. Yes, you'll have to extend the AD schema in order for AD to support Exchange 2007, but this step comes later in the process (see the "Final AD Preparation" section below). Right now, you need to make sure the individual domain controllers (DCs) are ready for Exchange 2007.

First, you should verify that your AD's schema master is running Windows 2003 SP1. You can identify the schema master by inserting your Windows 2003 installation CD-ROM into the server's CD-ROM drive and double-clicking the adminpak.msi file found in the CD-ROM's I386 directory. Windows launches the Administration Tools Pack Setup Wizard. Follow the wizard's prompts to install the administration tools pack.

When the installation process is complete, close the setup wizard and open Microsoft Management Console (MMC). In the console, select Add/Remove Snap-in from the File menu. Windows then displays the Add/ Remove Snap-in dialog box. Click Add on the Standalone tab to reveal a list of available snapins. Select the Active Directory Schema snap-in from the list, then click Add, Close, OK.

Now that the snap-in has been loaded, right-click the Active Directory Schema container in the console tree, then click Operations Master on the shortcut menu. As Figure 1 shows, you'll see a dialog box that tells you which server is acting as the forest's schema master. After you've found the schema master, simply right-click the My Computer icon for that server, then select Properties to display the System Properties sheet, which tells you the server's OS and service pack level.

The next step in preparing AD for Exchange 2007 is to verify that the Global Catalog (GC) servers and sites containing Exchange servers are running Windows 2003 SP1. You don't necessarily have to track down GC servers; a better method is simply to verify that every site containing an Exchange server has at least one DC running Windows 2003 SP1. A couple of advantages come with this requirement. First, running Windows 2003 SP1 on your DCs lets users browse the Address Book through Microsoft Outlook Web Access (OWA). Also, administrators are able to look up distribution list memberships more efficiently.

While we're on the subject of GC servers, this is a good time to decide whether yours are up to par. If your AD contains more than 20,000 objects, you'll get better performance by running a 64-bit version of Windows 2003 on your GC servers.

The last step in preparing AD (at least for now) is to make sure the functional level for any domains that will contain Exchange 2007 servers is set to Windows 2000 native or higher. Of course, it's preferable to have a domain functional level of Windows 2003, but you'll have to use the Windows 2000 functional level if the domain contains Windows 2000 Server–based DCs.

To check a domain's functional level, open the MMC Active Directory Users and Computers snap-in. Right-click the domain in the console tree, and select Raise Domain Functional Level. You'll see a dialog box (which Figure 2 shows) that displays the current functional level. If the domain is set to a functional level lower than Windows 2003, the dialog box gives you the option to raise the functional level.

Preparing Your Exchange Organization
After you've done your initial prep work on AD, it's time to turn your attention to your existing Exchange organization and determine the scope of your upgrade. For example, are all your Exchange servers being upgraded to Exchange 2007, or is the upgrade limited to a particular subset of your Exchange organization?

By far the most important consideration is whether you have Exchange Server 5.5 servers present in your organization. Exchange 2007 isn't compatible with Exchange 5.5. Therefore, any Exchange 5.5 servers must be upgraded at least to Exchange 2000 before you can bring Exchange 2007 into your organization.