[apimis]

I am planning to upgrade and migrate our exchange environment from 2003 at one site and 2007 at the other to 2010 in both. I am looking for any advice to accomplish this in a gradual fashion to move just over 200 mailboxes.

Current configuration is:
Site1.domain.local W2K3 Exchange 2003 standard (active)
Site1.newdomain.local W2K8 Exchange 2010 (not active)
Site2.domain2.local W2K3 Exchange 2007 standard (active)
Site2.newdomain.local W2K8 Exchange 2010 (not active)

All three domain are currently in use on the network and we have 2 way non-transitive trust set between the 3 domains.

The plan is to gradually migrate site1.domain.local over to site1.newdomain.local and to have them both up and running during the migration. I will have the same setup at site2. I will ultimately have the 2 2010 exchange servers on newdomain.local handling all mail traffic. I also would like to have it setup so the if one site went down it wouldn't effect the other and possibly have the site that's up take over for the site that's down. I am not sure about this functionality due to Exchange being the standard version vs enterprise.

Thanks for any advice!

[Sembee]

The version of Exchange has no impact on the ability to use high availability.
The impact is the version of Windows - it needs to be Enterprise edition.

With only two servers though, you will not be able to have one server take over from the other in any reliable manner. This is because the most common issue will be the loss of the connection between the servers. This causes a split brain scenario. If you want both locations to operate independently and have the data in another location, then you will need four servers.

With regards to the migration itself, you need to look at the cross forest migration techniques which are documented on Technet. If you cannot use cross forest then you are looking at a more complex migration involving PST files for moving the data and then setting up the environments for sharing the SMTP address space. It takes some planning to do it without any business disruption and hiring an experienced consultant may be the best option.

Finally, if you are yet to purchase Exchange 2010, then I would strongly suggest you add Software Assurance to the licenses as a new version of Exchange is due.

Simon.