The Road to Exchange 2010: Migration paths
Exchange always had a specific combination of operating systems on which it could be installed. Now with the release of Exchange 2010 RC1,Windows Server 2008 R2 and the imminent Exchange 2007 Service Pack, it has become clear how the future will look like. Below is a table which visually shows the compatibilities:
So unfortunately, Exchange 2007 will not run on Windows Server 2008 R2… That has impact on your possible migration (officially transition) paths to Exchange 2010.
First, what migration paths did we have in the past and present? Exchange 2000 was in-place upgradable to Exchange 2003. If Exchange 2000 was installed on Windows 2000, you then could in-place upgrade to Windows 2003 with taking al those benefits that come with that. An in-place upgrade from Exchange 2003 to Exchange 2007 wasn’t possible, mostly due to the required x64 OS for Exchange 2007. And an in-place upgrade from a 32bit OS to 64bit OS isn’t possible. Migrating to Exchange 2007 is directly supported from Exchange 2000 and 2003.
What about migrating to Exchange 2010? The Active Directory requirements are the same as with Exchange 2007. Another important requirement for migration to Exchange 2010 is that you at least have to have Exchange 2003 SP2 or Exchange 2007 SP2! So no co-existence with Exchange 2000. What kind of consequences will that have on your migration path? I know that a lot of businesses still use Exchange 2003 and even now some still use Exchange 2000, which makes it a very valid question.
Well, simply put: you will have to migrate from Exchange 2007 with Service Pack 2 on either Windows 2003 x64 or 2008 x64 (non R2!) or you have to in-place upgrade or transition your Exchange 2000 installation to Exchange 2003 SP2. Alternatively, you can transition directly from Exchange 2000 to Exchange Server 2007 SP2 and then transition to Exchange 2010. Note that an in-place upgrade of Exchange 2007 to Exchange 2010 isn't supported.
I’ve made an illustration depicting the migration paths:
Conclusion: There are no real problems migrating to Exchange Server 2010, they are comparable to the paths you had to take with Exchange 2007. Extra steps have to be taken if you are still using Exchange 2000. And for those who already migrated to Exchange 2007, will have to wait for Service Pack 2 which is expected at the end of this month.
For those who want all servers to be Windows 2008 and have an Exchange server, you will have to wait for Exchange 2010 RTM which will be probably released later this year or you decide to run Exchange 2007 on non-R2 Windows 2008.
Oh, and for those daredevils who are migrating to the Exchange 2010 RC1… You can in place upgrade to RTM!
Planning Checklist for Exchange 2010
Exchange 2010 System Requirements