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Alexander Zammit has been developing server applications for over 15 years. Most of his works involve Exchange integrated applications, including a FAX server, a mail security product and anti-spam products.
An Exchange 2007 upgrade must be planned so as to retain full functionality and minimize downtime. In this upgrade we moved a single Exchange 2003 to a mixed configuration whilst retaining OWA public folder access and third-party applications running on Exchange 2003.
It's been six months since Exchange 2007 was RTMed and more organizations are today starting to evaluate their upgrade options. There are many roads leading to Exchange 2007. These clearly vary depending on the starting point i.e. the initial MS Exchange Organization being upgraded. These also depend on the upgrade path most suitable to an organization that may include a long phase of mixed Exchange version coexistence.
Recently I went through a relatively simple upgrade. This was a single server organization that wanted to start moving to Exchange 2007. I expect this to be a very common scenario and thus decided to document the stages we went through.
The goal here was to install Exchange 2007 and transfer all mailboxes from Exchange 2003. The organization wanted to retain the Exchange 2003 machine for a couple of reasons, OWA public folder access and some third party email filtering applications. These applications will be retained until upgrade time arrives for them as well.
The first step was to make sure the domain and the current Exchange organization were ready for the upgrade. Exchange 2007 requires the domain functional level to be at least Windows 2000 native. This means that all domain controllers must be running Windows 2000 or later. Furthermore the Exchange Organization must be in Native Mode, meaning that all Exchange servers must be running Exchange 2000 or later.
The network already satisfied both requirements. All that was needed was to change the configuration from AD Users & Computers, and the Exchange System Manager.
Open AD Users & Computers
Right-Click the domain root and select Raise Domain Functional Level
From here select Windows 2000 native and click Raise
Open Exchange System Manager
Open the properties for the Organization node
Click Change Mode to switch from Mixed to Native mode.
Next was the turn of Exchange 2007. I will go fast forward through this highlighting the salient steps. The Exchange 2007 wizard is very good in making sure you don't miss any requirements. Also the general Exchange installation steps were described in an earlier article.
We got a brand new 64-bit machine, installed Windows 2003 x64, added IIS and World Wide Web service, installed SP2 and joined it to the domain. Next we added .NET Framework version 2, the Windows PowerShell, and went through the Microsoft Updates service until all the latest updates were in place.
Similar to earlier Exchange versions, Exchange 2007 allows you to prepare the domain and schema via command line. This is done through the setup.com executable, which supports a number of parameters for different preparation stages. The most commonly used option is /PrepareAD that will in most scenarios take care for all preparation steps. However for complete details it is best to go through How to Prepare Active Directory and Domains.
Performing a separate AD preparation stage is most useful in larger organizations where the FSMO roles are distributed over a number of servers and sometimes these literally get lost! Furthermore the preparation is helpful when the Exchange administrator does not hold the Schema Admin right and needs the assistance of another administrator. Sometimes there is also the need to troubleshoot AD replication problems. If your organization falls in this category, you will find useful my freeware tool discussed in Active Directory Health Check with AD Schema Diagnose.
Being a small organization, we decided to do everything at one go and proceeded to run the Exchange 2007 installation wizard. The steps were very similar to those described in our earlier article on Installing Exchange 2007 Beta 2. We chose the typical installation option for Hub Transport, Client Access and Mailbox server roles.
Also since we were joining an existing Exchange Organization, the name of the Exchange 2003 server was required for the setup of a routing group connector (more on this shortly).
Finally with a series of clicks on the Next button we completed the Exchange 2007 installation.
Administrators of single server Exchange 2000/2003 configurations usually are not concerned with issues related to internal email routing. With a single server the Exchange Organization is composed of a single Administrative Group and a single Routing Group. On Exchange 2003 these are by default hidden from the ESM UI.
Upgrading to Exchange 2007 and getting into coexistence leads to a more complex environment. Exchange 2007 servers must be kept in their separate Administrative and Routing group segregated from servers running earlier Exchange versions.
This is bad news for those administrators who took a nap during the lessons covering aspects typically associated with larger organizations. However the new setup is really not that difficult to understand. Plus the installation should have immediately created the routing group connector allowing for emails to flow between Exchange servers.
To see how the Organization is now structured, open the ESM on the Exchange 2000/2003 machine. The upgrade would have automatically rendered Administrative Groups visible. To uncover the Routing Groups and the newly created Routing Group Connector again go to the ESM Organization node properties and select 'Display routing groups'. Collapsing the tree nodes should show something like this:
In this simple upgrade scenario there should be no need to touch this routing configuration. However it is good to know that emails will now be flowing across Exchange servers through these connectors. Furthermore, do make it a rule never to change configuration settings for Exchange 2007 from the Exchange 2000/2003 ESM interface.
This completes the first stage of our upgrade. We now have Exchange 2007 coexisting with Exchange 2003. There is still more work to do. Next we have to start moving mailboxes. We also need to do extra work to satisfy our initial requirements and deal with routing problems that will crop up on the way. All this will be cleared in the second part.
How to Prepare Active Directory and Domains
Installing Exchange 2007 Beta 2
Active Directory Health Check with AD Schema Diagnose
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