Local Continuous Replication is a database replication tool new to Exchange 2007 Server. Local Continuous Replication (LCR) is built into Exchange 2007 and replicates the Storage Group Databases to a backup location. The backup location needs to be local to the server where the "Mailbox" role is hosted. The backup location can be another disk in the same computer, or an externally attached storage system. You can also replicate the databases to the same disk as the live Storage Group databases, but that provide as much value.
LCR asynchronously replicates all changes to the primary databases by sending transaction log files to the backup location as changes occur. The transactions in the log files are then applied to the backup database, keeping them virtually in sync with the primary databases. LCR is very similar to SQL Server Log Shipping, except it is not intended to replicate to remote systems.
While LCR is not a replacement for regular backups, it can have a significant impact on your backup and recovery strategy for Exchange 2007. Since your data is being replicated continuously, the need for daily backups of your Exchange 2007 databases is reduced for most organizations. With LCR your data is protected against hard drive failures and disk corruption. In the event of a loss or corruption of your primary database, Exchange 2007 can be manually switched to the backup database within minutes with little or no data loss. Taking regular full backups and storing backup copies off site is still very necessary, but you may find that your organization has reduced requirements for daily backups.
See Local Continuous Replication for more information.