Mission Impossible: In-Place Upgrading Microsoft Exchange Server 2007 from Windows Server 2003 to Windows Server 2008

Arne, you do have another option for migrating a clustered mailbox server (CMS) from Windows Server 2003 to Windows Server 2008.  It is option 1 mentioned above, where you install a new cluster, and then use our Move Mailbox tools to move the mailboxes from the old CMS to the new one. This has the benefit of less downtime per user, because each person is only offline while their mailbox is being moved. Whereas, with database portability, everyone is offline until the whole database is migrated. This also has the benefit of not having to touch desktop messaging profiles, as the original CMS will be online, it will redirect clients after their mailboxes have been moved, and it will cause their desktop profiles to be updated with the new CMS name automatically.