We will be installing our first Exchange 2010 SP3 server soon. We have 3 Sites all connected by high speed 10GB links. It really can be considered one big Site. Not sure why its separated other than they are different locations. We are considering collapsing our Prod Site and DR Site into one Site because we have the bandwidth. Other than the fact that the VM's are in different locations, they may as well be in the same datacenter with a 10GB link. We have redundancy also in case the 10GB link goes down. I was going to put one mailbox server and 1 CAS server in the Prod Site. 1 Mailbox server and 1 CAS server in the DR Site but have mailboxes on both. Its kind of a DR/Prod Site. The FSW will go on a server (non-exchange) in another Site. The reasoning is if our Prod Site loses power, the mailboxes should fail over to our DR/Prod Site and we will still have quorum because the servers in the DR/Prod Site can access the FSW. My only concern is I have never had a FSW in a different Site than the Exchange server and if this is allowed by Exchange.