All servers in this scenario are or will be running MS Server 2003 or MS Server 2008 and, when applicable, Exchange 2007.
I currently have 3 sites in our WAN - Admin (13 PCs), Site2 (10 PCs) and Site3 (10 PCs). I also have a couple of laptops that move around within the organization. I have about 50 users in AD. I currently have 1 Exchange Server that is also a Domain Controller (I know MS doesn't recommend this) and soon-to-be also a file & print server.
Site2 & Site3 have very slow response for Outlook & shared file access. I have 2 main goals: 1 - Increase speed at Sites1 & 2; and 2 - Have data replicated at the three sites so we have near-zero down time in the event of a catastrophe at Admin. I have conflicting recommendations from contractors.
My thinking is to build 2 new servers, each with Exchange and have 3 Exchange servers - one at each of the 3 sites. These same servers would host AD & DFS to keep a copy of all shared files at all 3 locations. Users would then authenticate, receive e-mail and access shared files on their respective LANs. The WAN would be utilized to replicate e-mail and shared files - and to access the Internet.
One contractor thinks the above scenario is OK, but has doubts that I am protected in case of catastrophe. If all 3 servers have replicas of all the relevant data, where am I unprotected? I understand the e-mail delivery point would have to be changed.
Contractor two thinks the above scenario will bring the WAN connection at Admin to a crawl and cause Admin personnel large delays in their Internet access. (I currently have 384k upload speed, but can increase this to 768k. Download is currently 3M, but I can increase to 6M.) This contractor suggests converting to terminal services, having all users access the term server at Admin for everything. I think this is riskier due to the single point of contact. We have volume licenses for XP & Office 2007 and can purchase the term server CAL's for $6 each, so we could convert to term servers if that's the best option. Would I place mirrored servers at Admin for data protection? Would I want/need domain controllers at the branches (we have none now)? Would my first scenario really make the WAN at Admin crawl?
Regarding e-mail, is there a better solution than on-site Exchange servers, assuming Exchange is the software, and full Oulook functionality is desired (i.e. not OWA)?
Any insight would be greatly appreciated.