If you’re like most Exchange administrators, you’ve been following the development of Exchange Server 2007 since the early beta versions and are eager to migrate to it. However, before you insert the installation DVD, you need to know some facts about Exchange 2007 and make some preparations.

The Facts
Exchange 2007 includes many changes and new features. Here are some changes and features that will affect your migration to this new release:

The product is 64-bit only. You must install Exchange 2007 on 64-bit hardware that's running a 64-bit Windows OS. It’s likely that any server you’ve purchased in the past two years is 64-bit capable. If you’re not sure, you should check with your hardware manufacturer or download a free CPU identification utility named CPU-Z from CPUID. (Note that you can’t run Exchange 2007 on Intel Itanium IA64 processors.) Although a 32-bit build of Exchange 2007 is available, Microsoft doesn't support its use in production environments, except for the installation of the management components on 32-bit Windows XP workstations.

Using 64-bit servers means different considerations when sizing disk and memory I/O. You need to make sure that your 64-bit servers are sized appropriately so that they can handle your particular Exchange organization. The Microsoft Exchange Team Blog has some informative articles about these considerations. Using the site's search functionality, search for “Exchange 2007 sizing” to obtain a helpful collection of articles about this topic.

There are five server roles. Exchange 2007 provides five server roles: Mailbox, Hub Transport, Edge Transport, Client Access, and Unified Messaging. For a concise look at what these server roles are, take a look at John Savill’s Web-exclusive FAQ "What are the Microsoft Exchange Server 2007 server roles?".

Message routing is based on Active Directory (AD) sites. With Exchange 2007, you no longer have to maintain separate routing groups for your message flows because AD sites are used for message routing. Exchange 2007 Mailbox servers look for a Hub Transport server in the same site. Messages are then relayed from that Hub Transport server to a Hub Transport server in the destination AD site. If an AD site contains a Mailbox server but no Hub Transport servers, mail won’t flow to that Mailbox server. A direct connection from one Hub Transport server to another won’t be made if a hub site is located along the path with the lowest routing cost, which you can use to control routing. AD sites are still used, however, to locate Hub Transport servers. If a connection can’t be made to the Hub Transport server in the destination AD site, the message will be delivered to the first Hub Transport server that responds going backward along the least-cost route. (For more information about this topic, see the Microsoft article "Planning to Use Active Directory Sites for Routing Mail".)

Because of this new message routing system, you should make any changes to your AD site topology prior to an Exchange 2007 migration. Similarly, you should make routing group modifications prior to migration. When you migrate, both the AD site and routing group topologies need to be efficiently deployed and well documented . Paul Robichaux’s Exchange & Outlook UPDATE article "Mixing Exchange 2003 and Exchange 2007" contains more information about this subject as well as links to Microsoft documentation.

Free/busy data is no longer stored in public folders. Although Exchange 2007 includes public folders, Microsoft recommends not using them because they might not be around in future Exchange versions. In addition, you can't manage public folders through Exchange 2007's Management Console. You need to use the Management Console in Exchange 2003 or PowerShell in Exchange 2007. So, if you have a public folder infrastructure, you might consider removing it and using a solution such as Windows SharePoint Services or Microsoft Office SharePoint Server 2007 instead.

Everything can be done from the command line. And some things can only be done from the command line. All the Exchange 2007 management tools are front ends for PowerShell. Anything you can do in the GUI you can do from the command line. Some tasks, such as enabling or disabling a user for POP3 or IMAP4 access, can only be done from within PowerShell. PowerShell is a powerful environment that you should look into. Knowing your way around PowerShell can help you migrate to Exchange 2007.

Migration from Exchange Server 5.5 to Exchange 2007 isn't supported. You can’t migrate directly from Exchange 5.5 to Exchange 2007. If you’re still on Exchange 5.5, you need to migrate to Exchange 2003, then migrate to Exchange 2007. Your Exchange organization must be native mode (i.e., contain only Exchange 2000 Server or Exchange 2003 servers).

The Preparations
Before you begin your migration, you need to make the proper preparations. Those preparations might include:

  • Updating existing antivirus, antispam, and backup software to Exchange 2007-aware versions. Your migration can’t proceed until your particular vendors have released this software. Keep in mind that the new message-hygiene features and the Edge Transport server role might mitigate the need for a separate antispam installation. For example, if you currently have an Exchange 2000 or Exchange 5.5 system and your third-party antispam solution is outdated or no longer meets your needs, you might consider using Exchange 2007's built-in antispam features as a replacement for your existing solution, even though that solution still works. Similarly, the new storage group (SG) replication features in Exchange 2007 might make you rethink your backup strategy. For example, if you decide to set up a cluster continuous replication (CCR) environment, you might want to start performing full backups weekly instead of daily because you would now theoretically need a failure of both the active storage group and the passive storage group before needing to restore files from a backup.
  • Updating existing fax gateway and mobile messaging software to Exchange 2007-aware versions. Your migration can’t proceed until your particular vendors have released this software. However, for mobile messaging software (e.g., Research in Motion's BlackBerry Enterprise Server), you might consider migrating all your servers except one. On that Exchange server, you can continue to host the user mailboxes that utilize the existing mobile messaging solution until the updated version is available.
  • Determining whether you want to migrate to Exchange 2007 Unified Messaging. If you have a unified messaging (UM) solution (e.g., Cisco System's Cisco Unity) in place, you need to decide whether to keep your current solution or migrate to Microsoft’s offering. If you plan to switch over to Exchange 2007 Unified Messaging, make sure you have a plan for routing calls and voicemail messages to the appropriate solution during the migration. You don't want to have hundreds of users not getting their calls and voicemail messages.
  • Planning for coexistence. In all but the smallest of organizations, your migration will be done over the course of a few weeks or even months. Third-party software will need to function with both Exchange 2007 and Exchange 2003 during this time, so you need to make sure your third-party software supports Exchange 2007.
  • Budgeting appropriately. Besides the cost of 64-bit hardware, make sure you include the cost of any additional hardware that you'll need. For example, you might have included the cost of a new fax gateway and a new server to run it on, but the fax gateway will be useless if you don’t have funds to buy the $20,000 intelligent fax board that you need. And besides the cost of a 64-bit Windows OS, you need to include the cost of any additional Microsoft or third-party software and any support contracts that need to be purchased or renewed. For example, if you plan to use SharePoint Server instead of public folders, your budget needs to include funds for obtaining the SharePoint software and any additional server hardware you might need.

Microsoft will be supporting Exchange 2003 for a long time, so there’s no need to rush into migrating to Exchange 2007. Proper preparation will ensure that your migration to Exchange 2007 is a smooth one. Consider installing a test environment so that you can play around with the product. In “Run Exchange 2007 Under Virtual Server 2005” (September 2006), I outline the steps I took to test the beta 1 release of Exchange 2007. You can follow these instructions to set up a test environment, except use the final version rather than the beta version of Exchange 2007.

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