Exchange 2010 combines the key availability and resilience features of cluster continuous replication (CCR) and standby continuous replication (SCR) into a single high availability solution that handles both on-site data replication and off-site data replication. Mailbox servers can be defined as part of a Database Availability Group to provide automatic recovery at the individual mailbox database level instead of at the server level. Each mailbox database can have up to 16 copies.
The following features in Exchange 2007 and Exchange 2007 Service Pack 1 (SP1) no longer exist in Exchange 2010:
Local continuous replication (LCR)
Single copy clusters (SCC)
For more information about this see: