A. Whereas Exchange 2003 really offers only one type of clustering support (local, with multiple servers sharing a SAN), Exchange 2007 supports log shipping both remotely and locally, which opens up new modes of clustering:

• Local Continuous Replication (LCR ), a single-server solution in which the system uses the logs to create a second copy of a storage group (SG) on a different set of disks. This method gives you a second copy of the data. (For more information, go here.)
• Cluster Continuous Replication (CCR), a two-server solution in which the system ships the logs to a second server to maintain a second copy of the SG. This second server can be local or remote. For more information, go here.)
• Single Copy Clusters (SCC), the same idea as Exchange 2003 clusters, in which one set of data is connected to multiple servers. For more information, go here.)