Two Strategies for Moving from Exchange 5.5 to Exchange 2000

First, thank you for your tremendous response to our "Give Us Your Feedback" issue last week. We received many responses, and they keep coming in. If you haven't responded to our feedback questions from last week, please take a moment to do so by going here and using the "Post a Comment" option. I've received a significant number of inquiries (based on our four-part "When Companies Merge" series) regarding migration scenarios from a Windows NT 4.0/Exchange Server 5.5 environment to a Windows 2000/Exchange 2000 environment. This week, I look at two different approaches to moving to Exchange 2000.

Most of you indicated (in your feedback from last week) that you haven't moved to Exchange 2000 but will probably move at some point. One of the other feedback questions I posed was about the status of your Win2K account migration. This key step is vital to Exchange 2000 migration, but it doesn't mean you have to move your entire infrastructure to Win2K; it's just easier if you've migrated your account domains from NT 4.0 to Win2K. If you haven't finished your account migration, you'll have more cleanup work and complexity later. The other key migration step is deploying the Active Directory Connector (ADC). The ADC is crucial for letting your Exchange 2000 and Exchange 5.5 users interoperate during the migration process. You must deploy the ADC and configure the connection agreements for each of your sites (ideally). These preparatory steps will ensure minimal complications and simplify your migration to Exchange 2000.

The first approach to Exchange 2000 migration involves upgrading Exchange 5.5 servers in place to Exchange 2000. Of course, this approach requires that you upgrade your servers to Win2K and might be an opportunity to restructure your NT 4.0 environment and collapse NT 4.0 resource domains into Win2K Active Directory (AD) top-level domains (convert NT 4.0 BDCs to Win2K member servers). When you upgrade Exchange 5.5 servers to Exchange 2000, the Exchange 2000 setup program takes care of most requirements. The setup program automatically creates an ADC Configuration Connection Agreement (CCA), replaces the Exchange code, and even upgrades the databases to the new Exchange 2000 structure. After you've upgraded the server, users can connect to their new Exchange 2000 mailboxes. This approach, while simple, is also very hard to back out of and represents a greater potential for user downtime than other upgrade methods.

The second approach to Exchange 2000 migration is the move-mailbox approach (affectionately known as the PACMAN approach). When using this method, you add Exchange 2000 servers to the Exchange 5.5 sites and relocate mailboxes from Exchange 5.5 servers to Exchange 2000 servers. This method is a low-impact solution when you have only one mailbox or group of mailboxes to move, and the back-out options are simpler. Of course, you also need extra hardware to use this approach.

Both of the above techniques require that you complete the NT 4.0 to Win2K account migration. If this migration hasn't happened yet in your organization and you want to move forward with Exchange 2000 migration, you'll have to use a hybrid approach to these two methods. This hybrid approach varies widely from organization to organization but will most certainly be messy. However, this area is where Microsoft and third-party tools from NetIQ, FastLane, and BindView really shine. If the hybrid scenario is your only choice, my advice is to work with a third-party vendor to make your life easier. If you want more information about Exchange 2000 migration techniques, check out the Microsoft Exchange Web site.