Here is the background on my environment. Windows Server 2003 Standard functioning as a domain controller with Exchange 2003 server offering Exchange to clients in addition to Outlook Web Access using a go-daddy certificate. It receives email from a Barracuda Anti-Spam appliance (smtp is port forwarded to the Barracuda from the firewall) on the private subnet. I have installed a new VMware eSXi 5.5 server that will be hosting three VMs for my new environment. The first VM is a Windows Server 2012R2 Standard server that is also a domain controller and is currently fully functional and talking well with the 2003 domain controller. I have already transitioned the FSMO roles to the new 2012 DC.
My next step is to introduce an Exchange 2010 server to the environment so I can do a swing migration. I installed Windows Server 2012R2 Standard to be the new Exchange server and then realized that you cannot install Exchange 2010 on this version of the operating system. Some have said you CAN if you get Exchange 2010SP3 but details have been sketchy and I don't want any gotchas.
I am looking for advice as to which of my proposed scenarios would be the best for me.
1. Spin up a Windows Server 2008R2 member server box and install Exchange 2010 to it per guides and whitepapers I have found. Move mailboxes to it and run it this way for a few weeks and then decommission the Exchange 2003 server by uninstalling it from the Windows 2003 Server. Spin up another Windows Server 2012R2 box (which will be the permanent home of Exchange) and install Exchange 2013 to that one and migrate from the 2008R2 Exchange 2010 box to that one. Once that is complete, decommission the Exchange 2010 server and delete the 2008R2 box from the domain and dump the VM.
2. Spin up a Windows 2012R2 Standard member server VM and install Exchange 2010 to it (if this is possible ... I don't think it is but I am throwing it out there in case someone can confirm it IS possible) and migrate the mailboxes from Exchange 2003 to it. Decommission the 2003 Exchange server. Then, do an in-place upgrade from Exchange 2010 to Exchange 2013 on the Windows 2012R2 Standard box. If it isn't possible, would it make sense to install Windows Server 2012 Standard (NOT R2), Exchange 2010 and then do an in-place upgrade later to Exchange 2013?
If #2 is possible, it would seem to be the least painful.