Considerations when you upgrade to Exchange 2000 Server

When you are planning an upgrade from Microsoft Exchange Server version 5.5 to Microsoft Exchange 2000 Server, there are many factors that you need to take into consideration, many of which are discussed in this article. This article is by no means all-inclusive, rather, it is intended to make you aware of potential issues that you may face in your upgrade.

The "More Information" section provides some points to consider and some common problems that you may encounter during an upgrade.

General Considerations

Upgrading from Exchange Server 5.5 to Exchange 2000 is a very complex task. Much of the complexity comes from the fact that the architecture for the product has changed considerably. Exchange 2000 integrates with Microsoft Windows 2000 Active Directory, using it for all directory-related services that were previously handled by the Exchange Server 5.5 directory. Also, all of the Internet protocols for Exchange 2000 are integrated with Microsoft Internet Information Services (IIS). Therefore, an upgrade from Exchange Server 5.5 to Exchange 2000 involves much more than just upgrading the messaging software; it requires Windows 2000 Active directory to be deployed and functioning properly, the Domain Name System (DNS) infrastructure to be designed to support Active Directory, and IIS to be properly installed.

Be aware that it is not possible to join an Exchange Server 5.5 computer to a site or Administrative Group that contains only Exchange 2000 servers. Keep this in mind when you are deciding to upgrade the last (or only) Exchange Server 5.5 computer in the site. Because some of the connectors to foreign messaging systems (such as PROFS, SNADS, DRAS) are not available in Exchange 2000, you may need to consider keeping an Exchange Server 5.5 computer in your site for the purposes of running these connectors.

Before You Upgrade

• It is recommended that at least one Active Directory domain operate in native mode. This permits Exchange Server 5.5 distribution lists (DLs) to be mapped across to Universal Distribution Groups (UDGs) and Universal Security Groups (USGs) in Active Directory. The Active Directory Connector (ADC) is hard-coded to create UDGs, but the Exchange 2000 information store can and will convert these to USGs on an as-needed basis. You can configure a secondary recipient connection agreement to replicate only DLs to the target native mode domain where USGs can exist. If UDGs exist in a mixed-mode domain, they cannot be converted into USGs, and your public folder permissions will not work.
• There are several methods you can use to upgrade to Exchange 2000: an in-place upgrade, a Move Mailbox upgrade, or a swing upgrade. For additional information about a swing upgrade, click the following article number to view the article in the Microsoft Knowledge Base:
  264879� XADM: Upgrading to Exchange 2000--the Swing Upgrade Method
• For an overview of the process of how to set up Exchange 2000, click the following article number to view the article in the Microsoft Knowledge Base:
  262068� XADM: How to Set Up Exchange 2000
• Make sure that you have applied the recommended hotfixes to your Exchange 2000, conferencing, domain controller, and global catalog servers:
  271976� Hotfix Rollup Package Corrects Problems in Q257357 and Q271907
• Make a back up of your Exchange Server 5.5 computer.
• Install the NNTP service. Although it is not installed as a default Windows 2000 Server component, it is required for Exchange 2000 Setup.

During Your Upgrade

• If you have Exchange Server 5.5 Service Pack 4 (SP4) installed, you will be prompted to overwrite the files described in the following Microsoft Knowledge Base article:
  282309� Upgrading Exchange Server 5.5 Service Pack 4 to Exchange 2000 Server

After You Upgrade

• If users get errors when they update free-and-busy information after the upgrade, click the following article number to view the article in the Microsoft Knowledge Base:
  286783� Error message updating free and busy data in Exchange 2000 Server
• After you upgrade from Exchange Server 5.5 to Exchange 2000, if MAPI clients such as Microsoft Outlook can no longer log on, click the following article number to view the article in the Microsoft Knowledge Base:
  288840� Mailboxes not accessible after upgrade to Exchange 2000
• For information about rolling back an upgrade that did not work, click the following article number to view the article in the Microsoft Knowledge Base:
  264309� How to roll back a failed upgrade from Exchange Server 5.5 to Exchange 2000

For additional information, see the following documents on the Microsoft Web site: