I still run in many discussions about Enterprise Architecture. In general you could say that its designed for high availability and increase of performance.
In an enterprise scenario, you would use clusters for your Microsoft SQL database and your SRS. The clustering usually connects to storage vault like NAS or SAN etc. The Microsoft CRM server is divided in application and platform server.
The application server make use of network load balancing, which gives you the option to use several application server. The platform server cannot be used in same setup as the application server. An high availability or fallback scenario would be an custom solutions. The solution will depend on what kind of workflows you are using in the crm application. Nevertheless its important to consider this solutions because it can have impact on your application and integration functionality.
I will post some possible solutions later.