Exchange 2007 servers in a CCR or SCR configuration are protected from data loss by mailbox replication. Selected storage groups have their mailbox databases continuously replicated onto another identically configured Exchange 2007 server. The storage groups on the originating server are active and are in-use by the Exchange user population. The storage groups on the replicated server are passive and not used until activated either manually or automatically because of an unexpected failure of the active server. Exchange CCR or SCR allows two Exchange servers to be clustered together to create the active and passive nodes.
An example of how the databases may be protected in a CCR configuration is shown below. The database names shown in red are the active copies. Here, Exchange_South hosts all the passive database copies.