Throughout this chapter, we explored all the great enhancements made to Exchange 2013 in regards to site resilience. The removal of the limitation of CASs being bound to a single AD site, the introduction of a single and global namespace, and automatic failover at the client side all contribute to a much smoother datacenter recovery process with user impact being further reduced. As the recovery of a DAG is no longer tied together with the recovery of the client access namespace, each one of these components can be easily switched over between different datacenters without affecting the other component. This also allows administrators to place a witness server in a third datacenter in order to provide automatic failover for a DAG on either of the datacenters it is split across, something not recommended in Exchange 2010.

All in all, site resilience has come a long way and it is definitely one of the greatest improvements in Exchange 2013. In the next chapter, we will explore transport...