A comparison of the migration methods for migrating from Exchange Server 5.5 to Exchange Server 2003 or to Exchange 2000 Server (327928)

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Method 1: Move the mailboxes

One way to upgrade to Exchange 2000 or to Exchange 2003 is to move the mailboxes from an existing Microsoft Exchange Server 4.0 or Exchange Server 5.5 computer to an Exchange 2000 computer or to an Exchange 2003 computer. With this method, you install Exchange 2000 or Exchange 2003 in the existing Exchange Server site and then move all the mailboxes and the public folders to it.

To move the mailboxes from an Exchange 4.0 computer or from an Exchange Server 5.5 computer, you must have at least one Exchange Server 5.5 computer in that site. You can install Exchange 2000 or Exchange 2003 only in a site that has an Exchange Server 5.5 Service Pack 3 (SP3) or later computer. If you do not have an Exchange Server 5.5 computer in that site, you cannot install Exchange 2000 or Exchange 2003 in it.

Some advantages of this method include:

• The down time is minimal. The only down time is the time that it takes move the users' mailbox data. Because of this, this method is the preferred method of upgrading.
• You can directly upgrade users on Exchange Server 4.0 and Exchange Server 5.5 computers to Exchange 2000 or Exchange 2003.
• Not all users have to be upgraded at the same time.
• Client profiles are automatically reconfigured after the mailbox is moved and after the user logs on.

Some disadvantages of this method include:

• Older version connectors cannot be moved.
• The ExMerge utility cannot move Public Folder data.

For more information about this method, click the following article number to view the article in the Microsoft Knowledge Base:

Method 2: Use a swing upgrade

The swing upgrade method gives you the flexibility of the move mailbox method of upgrading, but with the swing method, you do not have to purchase new hardware for each existing server. With the swing method, an organization can purchase one or two new servers while they are upgrading the whole organization to Exchange 2000 or to Exchange 2003, and then the organization can use the move mailbox method to move data to the new servers. The old Exchange Server 5.5 computers are upgraded to or reinstalled with Exchange 2000 or with Exchange 2003, verified as stable, and then redeployed into production. At that point, the mailboxes are moved back to the original server hardware.

With the swing method, you can upgrade to newer, more powerful hardware, and then reintroduce it to the production environment with minimal disturbance to your users.

Some advantages of this method include:

• The down time is minimal. The only down time is the time that it takes to move the users' mailbox data.
• You can upgrade users on Exchange Server 4.0 and Exchange Server 5.5 computers.
• No operating system upgrades, Exchange Server upgrades, or hardware upgrades occur on the existing server until users are fully moved to another server.
• Client profiles are automatically reconfigured after the mailbox is moved and the user logs on.

Some disadvantages of this method include:

• You cannot move older version connectors.
• You cannot move Key Management Server (KMS).

For more information about the swing method in Exchange 2000 Server, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the swing method in Exchange Server 2003, click the following article number to view the article in the Microsoft Knowledge Base:

Method 3: Use an in-place upgrade

With the in-placed upgrade method, you can take an existing Exchange Server 5.5 SP3 or SP4 server and install Exchange 2000 on it. In this way, you upgrade your existing Exchange Server databases and connectors to Exchange 2000. When you use this method, you must perform all prerequisites and testing for the installation of Exchange 2000. If you do not do this, the result may be significant down time for your users and possible loss of e-mail data if you did not make correct backups.

Some advantages of the in-place upgrade method include:

• It offers the shortest migration time because all data is upgraded at the same time.
• It does not require any additional server hardware.

This method of upgrade can cause problems if you do not do all prerequisites for the upgrade and installation of Exchange 2000. This can cause significant down time for users.

If you must use this method of upgrade because of hardware availability limitations, we strongly recommend that you make backups before the upgrade in the form of online backups, offline backups, and backups in the form of personal folder (.pst) files by using ExMerge. With a backup in .pst format, you can run a clean installation of Exchange 2000, and then import your data directly from your .pst files if an in-place upgrade fails, instead of rebuilding your Exchange Server 5.5 server and restoring from backup. This method has the same disadvantages as the ExMerge method. At a minimum, an unsuccessful in-place upgrade recovery includes the following steps:

1. Manually remove Exchange 2000 from the server.
2. Manually remove Exchange Server objects from Active Directory.
3. Reinstall Exchange Server 5.5.
4. Restore Exchange Server 5.5 data from backups.
5. Troubleshoot to determine the reasons for the unsuccessful upgrade.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: For more information, see the "In-Place Upgrade from Microsoft Exchange 5.5 to Microsoft Exchange 2000" white paper. To view this white paper, visit the following Microsoft Web site:

Note Exchange 2003 can coexist with Exchange 2000, and when Exchange 2003 runs in Exchange mix mode, it can coexist with Exchange Server 5.5.

Exchange 2003 does not support in-place upgrades from Exchange Server 5.5. Exchange 2003 does support in-place upgrades from Exchange 2000. Although Exchange 2000 supports in-place upgrades from Exchange Server 5.5, the move-mailbox scenario that uses the Exchange 2003 Deployment Tools is the recommended upgrade method.

For more information about upgrading to Exchange 2003, click the following article number to view the article in the Microsoft Knowledge Base:

Method 4: Use the ExMerge utility

When you use the ExMerge upgrade method, you must:

• Export all your users' mailbox data to .pst files by using the ExMerge utility, and then export Public Folder data to .pst files on a Microsoft Outlook (MAPI) client.
• Remove Exchange Server from the existing server (if you are using the same server).
• Install Exchange 2000 or Exchange 2003.
• Import your mailbox and public folder data from .pst files.

Some advantages of the ExMerge method include:

• It offers a different recovery method, if an in-place upgrade is unsuccessful.
• It offers a way to help secure data from a failing server and run a clean installation of Exchange 2000 or Exchange 2003.

Some disadvantages to the ExMerge method include:

• You have to create new mailboxes for all users before the import.
• You have to re-create all permissions on Public Folders.
• You cannot reply to old e-mail messages from users on this server.
• You have to reconfigure all connectors.
• You have to re-create distribution lists.
• You have to re-create Custom Recipients.
• You have to create new Exchange Client Profiles at each user desktop. If the server name does not change, new Client Profiles may not be required.
• Any users with Offline Storage files (.OSTs) have to export them to .pst files before they connect to the new server.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Method 5: Use the Migration Wizard

You can use the Exchange 2000 SP3 version of the Migration Wizard (MigWiz) to migrate mailbox data from servers in either an Exchange Server 5.5 organization or an Exchange 2000 organization to a separate Exchange 2000 organization. When you migrate mailbox data from an Exchange 2000 organization by using the SP3 version of the Migration Wizard, new, turned-off user accounts are created in the target directory. If you decide to turn on these accounts, you must first use the Active Directory Migration Tool (ADMT) to migrate the accounts with security identifiers (SIDs).

The Migration Wizard uses a copy process that is similar to ExMerge; the source mailbox is not deleted or changed in any way by the migration process. The Migration Wizard is intended to be used between separate Exchange organizations, NOT in the same Exchange organization.

Some advantages of using the Migration Wizard include:

• You can migrate user mailbox data (including the Inbox, Drafts, Sent Items, Calendar, Tasks, Contacts, and Custom folders that were created by the mailbox owner) to a new Exchange organization.
• The wizard automatically creates new, turned-off user accounts in new domain.

Some disadvantages of using the Migration Wizard include:

• Mailboxes are associated with the user accounts in the old domain. This may be an advantage, depending on your requirements.
• You have to use .pst files to migrate public folders. Permissions have to be re-created.
• You cannot reply to old e-mail messages from users on this server.
• All connectors have to be reconfigured.
• Distribution lists have to be re-created.
• Custom recipients have to be re-created.
• New Exchange client profiles have to be created at each user desktop.
• Any users with .OSTs have to export them to .pst files before they connect to the new server.

For more information about this method in Exchange 2000 Server, click the following article numbers to view the articles in the Microsoft Knowledge Base: For more information about this method in Exchange Server 2003, click the following article number to view the article in the Microsoft Knowledge Base: