Exchange Migration

With Exchange Server 5.5 SP3, you can simply upgrade the databases. This requires taking the server offline and then running the Exchange 2000 Server Setup program.
The advantages of an in-place upgrade are that existing hardware can be used, and the existing data in the information stores is converted very rapidly, at approximately 8 GB per hour. This makes the upgrade process extremely fast. The speed of the database conversion depends on the number of folders that exist, and not on the total amount of data stored. The reason for this is that most of the upgrade time is spent by the access control list (ACL) upgrade process, which replaces Exchange directory access control entries with objects from Active Directory.
The disadvantages of an in-place upgrade are that the server must already be running Windows 2000 and Exchange Server 5.5 and the hardware must be capable of running Windows 2000 and Exchange 2000. Additionally, in-place upgrades may require more user downtime than other migration methods.

Several options are available for upgrading your existing Exchange servers to Exchange 2000. They are:
 Perform an in-place upgrade of your Exchange 5.5 servers.
 Install Exchange 2000 on new hardware and then migrate mailboxes and public folders to the new server.
 Use the leapfrog method, reusing hardware as the migration progresses throughout the organization.

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