Exchange upgrade: challenges ahead

Corporate users who migrate to Exchange 2007 will face mandatory infrastructure changes that, while advancing security and management, could add complexity and costs to their networks.

Beyond the 64-bit-only platform, major changes include a new role-based architecture that could require users to roll out as many as five types of Exchange servers to support functions such as remote client access, transport and routing, mailboxes, and unified messaging. The current versions of Exchange give users two deployment options: front-end servers and back-end servers.

Users also will face new clustering limitations and will have to eliminate all Exchange 5.5 servers from their environments. In addition, they will not be able to do in-place upgrades between Exchange 2000/2003 and Exchange 2007. And Exchange no longer will have its own site topology but will run on top of Active Directory topology.

In addition, Microsoft has yet to release detailed migration and best practices guidelines to users. The first public beta of Exchange 2007 is due by the end of July.

"More complex, yes," says Peter Exstrop, a network consultant for WM-Data. "Before, all the roles were on the same server, but now you will have more servers." Exstrop acknowledges nearly all the Exchange 2007 roles can be deployed on one server, but that will not be a viable option for larger deployments.

"But I look forward to splitting the server roles," he says. "Security is better, you don't have to have a complete Exchange server in your [demilitarized zone] to receive mail." With earlier versions of Exchange, servers in the DMZ were viewed as a security risk.

Another major area of change will be clustering. Users will be able to cluster only servers deployed in the mailbox role. Edge servers, which supply e-mail hygiene services such as anti-virus and anti-spam protection, will be required to run on a dedicated server and with Active Directory Application Mode.

"We had our routing [service] on a cluster, and now it needs to go somewhere else, and that means more servers," says Christopher Wenzel, applications analyst for law firm Katten Muchin and Rosemann. Wenzel, who has clusters running in four of his five Exchange sites around the United States, noted that best practice guidance from Microsoft for Exchange 2003 was to cluster servers. "In the past, the idea was server consolidation, but not anymore. Now it is scaling out again. My footprint increases in that I need more servers and more money for licensing" Exchange and Windows.

Microsoft has yet to release licensing option requirements for Exchange 2007.

Wenzel says the new Clustered Continuous Replication, which allows for geographically dispersed clusters and prevents against site failures, may be more than he wants.

"Most of my outages are not site failures. I don't want Exchange to fail over from Los Angeles to Chicago," he says.

But Wenzel says the need for unified messaging, a major new feature of Exchange 2007, is driving his upgrade plan, along with improvements in Outlook Web Access and search.

"We have never been afraid of upgrades. If they add to the productivity of our attorneys, then we think it is worth it," he says.

Microsoft is expected to introduce enough infrastructure changes that experts say users with multisite, multiserver Exchange installations must carefully plan their Exchange 2007 architectures.

"Users have to rethink the infrastructure stuff with front-end and back-end servers," says Peter Pawlak, an analyst with Directions on Microsoft. "Now it is all about client-access servers, mailbox servers, transport servers and unified messaging."

Pawlak says the changes should be positive for users, including tying Exchange to the Active Directory site structure.

"If the Active Directory site is designed correctly, this should make Exchange administration easier," he says. "Administrators no longer have two site structures to design."

The Exchange-Active Directory match isn't the only dependency in Exchange 2007.

Users will need at least one client-access server and one hub server in each site that contains a mailbox server. Those roles, however, can run together on the same server. And both those servers will have to be Exchange 2007 servers to support Exchange 2007's revamped Outlook Web Access client.

Users also might find that 32-bit, third-party plug-ins to Exchange, especially those that run on the server, may not run properly.

"Many of the 32-bit applications will run," says Dave Thompson, corporate vice president of the Exchange group at Microsoft. "But they will have to be considered on a case-by-base basis. The ones that won't [run on 32-bit] will need a compatibility kit."

For unified messaging, users will have to integrate Exchange with a PBX, and Microsoft has yet to detail the technical aspects of that union.

"It is not trivial connecting a PBX to Exchange, and people will not [change] out their PBX for this product," Pawlak says.