Installing Exchange Server 2010 into an existing Exchange Server 2007 environment

Before installing the first Exchange Server 2010 server into an existing Exchange Server 2007 environment, a number of prerequisites have to be met:

• All domains in an existing Active Directory forest have to be running in native mode.

• The Active Directory forest has to be running on a Windows Server 2003 forest functionality level.

• Each site in Active Directory should have at least one Domain Controller and the Global Catalog server on a Windows Server 2003 SP2 level. Although not enforced, it is recommended to have 64-bit type Domain Controllers and Global Catalog Servers for optimal performance.

• The Schema Master of the Active Directory needs to be a Windows Server 2003 SP2 or a Windows Server 2008 SP1 server. This can either be a 64-bit or a 32-bit server.

• All Exchange Server 2007 servers must have Service Pack 2 installed.

• The Internet facing Active Directory sites must be the first sites that will be upgraded to Exchange Server 2010.

Likewise, the physical server where Exchange Server will be installed needs to meet the following prerequisites:

• The server needs to be a 64-bit (64-bit, Itanium is not supported!) based computer.

• Windows Server 2008 SP2 or Windows Server 2008 R2 64-bit needs to be installed.

• Internet Information Server needs to be installed.

• Windows Remote Management (WinRM) 2.0 needs to be installed.

• PowerShell 2.0 needs to be installed.

• .NET Framework 3.51 needs to be installed.

Depending on the version of Windows 2008 you're using (i.e. Service Pack 2 or R2) a number of hotfixes need to be installed. I strongly recommend you bring your server up to date with the latest hotfixes from Windows Update.

1 Exchange Server 2010 order of installation

Exchange Server 2010 can be installed into an existing Exchange Server 2007 environment in the same forest and the same domain, but there are some issues with compatibility. You have to take the installation order of the Exchange Server 2010 servers into account to minimize the impact of this:

• First – Exchange Server 2010 Client Access Server. The Client Access Server can work with an Exchange Server 2007 Mailbox Server as well as an Exchange Server 2010 Mailbox Server.

• Second – Exchange Server 2010 Hub Transport Server.

• Third – Exchange Server 2010 Mailbox Server.

• The Edge Transport Server can be installed at any time, since an Exchange Server 2010 Edge Transport Server can be subscribed to an Exchange Server 2007 SP2 Hub Transport Server.

After you've installed the Mailbox Server role and established a proper Public Folder replication between Exchange Server 2007 and Exchange Server 2010, you can start moving mailboxes to the new Mailbox Server. Of course, the Public Folder replication needs only be configured when Public Folders are used in Exchange Server 2007.

Please bear in mind that an in-place upgrade to Exchange Server 2010 in any scenario is NOT supported!

2 Installing Exchange Server 2010

Although there's a specific order to the installation of server roles, these roles can, of course, be combined on one server.

When upgrading to Exchange Server 2010 the following steps need to be performed:

So, let's get started with the upgrade.

2.1 Upgrading Active Directory

Before you even think about installing server roles, the first step in upgrading the Exchange Server 2007 environment to Exchange Server 2010 is upgrading the Active Directory Schema. Bear in mind that it is also possible to use the graphical setup program, as this can be found on the installation media as setup.exe. When you use this program, all steps below are automatically performed. The command prompt system is mainly for people who want to retain more fine-grained control over their transition.

Once the Schema has been upgraded, the Configuration (which is stored in the Active Directory Configuration Container) can follow.

Figure 1. The Exchange Organization in the Configuration Partition of a pure Exchange Server 2007 environment.

The Exchange Server 2007 organization called "RUBS" can be seen in Figure 1. All Exchange Server 2007 servers are stored in the default Administrative Group Exchange Administrative Group (FYDIBOHF23SPDLT). If your Exchange 2007 has previously been upgraded from Exchange Server 2003, then it's very likely that you will see a First Administrative Group as well. If the upgrade was finished correctly, this First Administrative Group should be empty, or almost empty.

Exchange Server 2010 also uses the Exchange Administrative Group (FYDIBOHF23SPDLT), but there are differences in how Exchange Server 2010 works, for example, with databases. In Exchange Server 2007, a database is bound to a Mailbox Server, while in Exchange Server 2010 databases exists on the organization level, independent of any Mailbox Server. So when upgrading the Exchange Configuration, the Administrative Group is changed to facilitate both the Exchange Server 2007 environment as well as the Exchange Server 2010 environment.

When you want to change the Exchange Configuration, open a Command Prompt, navigate to the Exchange Server 2010 installation media, and enter the following command:

After upgrading the Exchange Configuration, some Exchange Server 2010 specific entries appear in the Exchange Administrative Group, like the Database Availability Group and the Databases container. This is more or less what you should see:

Figure 2. The Configuration Container after upgrading the Active Directory. The Exchange Server 2010 specific entries are clearly visible.

The next step is to prepare the domain (or domains if you have multiple domains that host user accounts with Exchange Server mailboxes) for use with Exchange Server 2010. To do this, open a command prompt, navigate to the installation media and enter the following command:

And if you want to prepare all domains in your environment, enter the following command:

Figure 3. Preparing the current domain for Exchange Server 2010.

When the setup /PrepareDomain is finished, the Active Directory is now ready to install the first Exchange Server 2010 server.

2.2 Installing the Exchange Server 2010 servers

As mentioned earlier, the only supported order of installation of Exchange Server 2010 server roles into an existing Exchange Server 2007 environment is as follows:

• Client Access Servers

• Hub Transport Servers

• Mailbox Servers.

Also, the Internet-facing Active Directory site, the site associated with your external Autodiscover record, should be the first to be transitioned. Then you should transition other Internet-facing Active Directory sites. The last sites you should transition are the internal Active Directory sites. Transitioning internal Active Directory sites before the Internet-facing Active Directory sites have been transitioned is not supported.

In our test environment, we are installing a combined Exchange Server 2010 Client Access Server role and Hub Transport Server role, and one dedicated Exchange Server 2010 Mailbox Server role.

First, ensure that Windows Server 2008 Server and all the prerequisite software is installed on the target server. To install Internet Information Server 7 (or 7.5 in the case of Windows Server 2008 R2) and other prerequisites, open a command prompt, navigate to the \Scripts directory in the installation media and enter the following command:

This will install Internet Information Server, as well as other prerequisites, with the right configuration for the Client Access Server and the Hub Transport Server.

To install the actual Exchange Server roles you can use either the command-line setup or the graphical setup. Right now, we will use the graphical setup program, and to open this setup application you just need to start the setup.exe program in the installation media.

2.3 Certificate installation

After the installation of the Exchange Server 2010 Client Access Server, the coexistence still has to be configured. Eventually, users will connect to the new Client Access Server and, if a user's mailbox exists on the new Exchange Server 2010 Mailbox Server, the request will be processed as usual. When the user's mailbox still exists on the Exchange Server 2007 Mailbox Server, however, the request is either forwarded to the Exchange Server 2007 Client Access Server, or processed by the Exchange Server 2010 Client Access Server, and the information retrieved from the Exchange Server 2007 Mailbox Server. This all depends on the protocol that's being used, but it is important for determining the certificates being used on the Client Access Server as explained below.

Outlook Web Access clients naturally connect to the Exchange Server 2010 Client Access Server. After validating the user's credentials, the Client Access Server checks the mailbox server and, if this is still running on Exchange Server 2007, the request is redirected to the Exchange Server 2007 Client Access Server.

After installing the Exchange Server 2010 Client Access Server, a new third-party certificate needs to be requested. A self-signed certificate is created by default during the setup of the Client Access Server, but this is not at all usable for a production environment. The certificate that ideally needs to be used on a Client Access Server is a certificate with multiple domain names, and these certificates are also known as Unified Communications (UC) certificates. The additional domain names are stored in the "Subject Alternative Names" property of the certificate. For more information regarding these certificates and a list of supported UC certificate vendors, you can visit the Microsoft website: HTTP://TINYURL.COM/CERTVENDORS.

This UC certificate should at least contain the following domain names:

• Webmail.inframan.nl – this is the primary entry point for all Outlook Web Access, Exchange Active Sync (EAS) and Exchange Web Services (EWS) requests.

• Autodiscover.inframan.nl.

• Legacy.inframan.nl – this is the namespace for the Exchange Server 2007 Client Access Server.

If you chose not to enter the external domain during setup (in the case of an Internet-facing Client Access Server) a number of external URLs will also need to be configured as explained in the next section.

2.4 Configure Exchange Web Services

Exchange Server 2010 uses the Client Access Server to offer the Offline Address Book and Free/Busy information using the HTTP protocol, and these can therefore be used by Outlook 2007 and Outlook 2010. To configure the Exchange services, open an Exchange Management Shell and enter the following commands:

In the coexistence scenario, the Offline Address Book generation server is still the Exchange Server 2007 Mailbox Server. We want to move this to the Exchange Server 2010 Mailbox Server, so we follow these steps:

It is also possible to move the generation server to Exchange Server 2010 using the Exchange Server 2010 Management Shell. On an Exchange Server 2010 server, open the Exchange Management Shell and enter the following command:

If your Exchange Server 2007 environment has Public Folders, it is likely that you will want these on your Exchange Server 2010 Mailbox Server as well. The Public Folder database is, in this case, automatically created, but you have to manually configure replication, which is a bit of a hassle.

Figure 5. Add the Exchange Server 2010 Public Folder database to the replication list.

Repeat these steps for:

• EX:/o=<<organization>>/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)

• OAB Version 2

• OAB Version 3a

• OAB Version 4

• EX:/o=<<yourorg>>/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)

• Schedule+ Free Busy: EX:/o=<<yourorg>>/ou= Exchange Administrative Group (FYDIBOHF23SPDLT).

3 SMTP Infrastructure

The Exchange Server 2007 Edge Transport Server needs to be transitioned to Exchange Server 2010 as well. Before doing so, you need to make sure the Active Directory has been transitioned first:

It's actually rather simple, although you should bear in mind that this is one of the rare cases when the relationship between Exchange Servers 2007 and 2010 is asymmetric! Specifically, an Exchange Server 2010 Edge Transport Server cannot be subscribed to an Exchange Server 2007 Hub Transport Server.

4 Moving mailboxes to Exchange Server 2010

Mailboxes should be moved from Exchange Server 2007 to Exchange Server 2010 using the 2010 version of the Exchange Management Console, or the Exchange Management Shell. Even more interesting, the new onlinemove mailbox functionality (now called MoveRequest) can be used, which results in a minimal downtime for the users. Even when they have a multi-Gigabyte mailbox!

During an online move-mailbox, a new mailbox is created on the Exchange Server 2010 Mailbox Server and the contents are synchronized between the old (on Exchange Server 2007) and the new mailboxes. The user is still working with the old mailbox and new messages still arrive at the old mailbox. When both mailboxes are in sync the old mailbox is closed, Active Directory is updated with information regarding the new mailbox location and the new mailbox on Exchange Server 2010 is fully up and running.

Lastly, note that the online move-mailbox functionality only works between Exchange Server 2010 servers, and when moving from Exchange Server 2007 to Exchange Server 2010. When moving from Exchange Server 2010 to Exchange Server 2007, the move is offline. It also doesn't work with Exchange Server 2003, which is a shame.

Either way, congratulations! You should now have Exchange Server 2010 running in Coexistence with either your Exchange Server 2003 or 2007 environment!