The main problem of the migration from Exchange Server 5.5 to 2003 is to move the Exchange directory service to Active Directory. Because Exchange Server 2003 new features are fully supported on Windows Server 2003 it is best to run this combination. In general there are two ways for moving to Exchange Server 2003. The first is to upgrade an existing Exchange 5.5 environment by running an inplace upgrade. Another way is to migrate the Exchange directory service to Active Directory and then implementing an Exchange Server 2003 environment.
With Exchange Server 2003 you can use a good structured wizard for a successful migration. This wizard could be run by using EXDEPLOY.CHM (Exchange Deployment Tools) from the Exchange Server 2003 CD.
Preparing your environment
After you have successfully implemented and deployed your Active Directory on Windows Server 2003 and all your Global Catalog Server are Windows Server 2003, you should then make sure that you have updated your Exchange Server 5.5 with Service Pack 3 or higher. If you have deployed Instant Messaging or Exchange Server 2000 Conferencing you should consider deleting them before you update these servers. They will be replaced with Office Live Communication Server 2003; even Mobile Information Server should be deleted, because now it is built in with Exchange Server 2003; so coexistence is not supported.
The next step means preparing your Active Directory by implementing the schema update. You have to log on to your domain as Enterprise Administrator and then run setup.exe with the forestprep switch having connectivity to the schema master. After a successful replication the next step is to prepare your domains in your forest using the domainprep switch on one domain controller of each domain logged on as Domain Administrator.
Installing and configuring Active Directory Connector
The next step is to install the Active Directory Connector from your Exchange Server 2003 CD in your environment. Then you have to configure the appropriate connection agreements for public and private folders. The account that has to be specified for running the Active Directory Connector should have service account permissions. The import and export process has to be configured using accounts that have the appropriate permissions to read and write to the specified directories. The configuration connection agreement is configured automatically and will make sure that Exchange Server 5.5 directory service will synchronize the complete configuration with Active Directory Services.
If you have already deployed ADCs Exchange Server 2000 in your environment, you have to upgrade them to Exchange Server 2003 ADC before you can start deploying Exchange Server 2003.
With the new Exchange Deployment Tool (EXDEPLOY.CHM) that you can find on your Exchange Server 2003 CD it is quite easy to do the migration, because this tool provides a step-by-step guide on the required actions.
The Move Mailboxes Process
Before you can start the Move Mailbox Procedure using Exchange Deployment Tools or “Active Directory Users and Computers” you should check whether there is a one-to-one relationship between your Accounts and Mailboxes. An easy way to check this automatically is to use the Ntdsattrb.exe tool that can be found on your Exchange Server 2003 CD, too. If so, you should suggest renaming your mailboxes before starting the migration. After a successful migration you can restructure your environment again and perform many-to-many relationships between mailboxes and users.
With Exchange Server 2003 you have a lot of improvements on moving mailboxes, in detail they are:
Up to 5 mailboxes can be moved simultaneously
No stop if corrupt messages have been found
Easier to schedule
Provides increased performance and reliability
Figure 3: Running “Moving Mailboxes”
Rehoming public folders
Rehoming your public folders means that you should replicate them to your new server and then cancel the replication with the old one. This procedure can be done by using Pfmigrate.wsf, too. Don’t forget to replicate your system folders. The pfmigrate script can do the whole procedure in one step using the following switches.
pfmigrate.wsf /S: /T: /N:20 /A /SF
ð This command replicates 20 system folders at a time from the source to the target server.
Pfmigrate.wsf /S: /T: /N:20 /R /SF
ð This command deletes the replicated system folders from the source server.
Moving your connectors
Each connector has to be moved manually. That means you should document the settings of your connectors and then reconfigure them in your Exchange Server 2003 organization. And don’t forget to change the MX records on your DNS servers, too.
Replacing OWA Front-End Server
Replacing your existing OWA Front-End Server will be very easy, because the new release will provide backward compatibility with Exchange Server 2000 and 5.5. The new look of Outlook Web Access will be provided to each user, if both – back and front-ends are on Exchange Server 2003.
Preparing to change to Exchange Server 2003 native mode
If there are no more private or public information stores nor connectors on your Exchange Server 5.5 you can start removing the last Exchange Server 5.5 from the your Exchange Server 2003 environment. But before you should start to remove the server you should stop all Exchange Server 5.5 services for some days to make sure you can run your email environment without any Exchange Servers 5.5. If everything works without any trouble you can then start the demotion process. Please make sure that all Exchange Server 5.5 services are stopped before you delete your Exchange Server 5.5 from your organization. This can be done by starting your Exchange 5.5 administration program and connecting to your Exchange Server 2003 and deleting your Exchange Server 5.5 directory object. After a successful replication of your deletion with Active Directory Connector you will not find any Exchange Server 5.5 objects in your environment anymore. But before you can delete the Active Directory Connector you have to delete the appropriate configuration connection agreement. The last but not least step is now to remove the ADC from your environment and to switch to native Exchange mode. With this step your demotion of Exchange Server 5.5 is being done.
If you are migrating an existing Exchange Server 5.5 organization to Exchange Server 2003 is not quite as easy as upgrading, but after the whole procedure you are having a complete newly reconstructed and completely overworked messaging and collaboration system without any old fragments of Exchange Server 5.5.
Because implementing Active Directory Services means a restructure of your network with server consolidation. Because Exchange Server 2003 supports about 4 times more users than Exchange Server 5.5, you should think of a migration of your users to Exchange Server 2003 with a complete redesign.