Applies to: Exchange Server 2007 SP3, Exchange Server
2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2006-09-20
This topic discusses the new high availability and clustering features in Microsoft Exchange Server 2007. These features include continuous replication and single copy clusters.
Continuous replication is present in two Exchange 2007 features that use built-in asynchronous replication technology to create a copy of a storage group and maintain the copy's currency through log shipping and replay. Replication facilitates this by applying the log files of a production database to a copy of that database. The two features that contain this technology are local continuous replication (LCR) and cluster continuous replication (CCR).
- Local continuous replication LCR lowers
the total cost of ownership for Exchange 2007 by reducing the
number of regular backups that are required for data protection.
Although LCR does not eliminate the need to take backups (data
backup are important to have if a disaster strikes), it does
significantly reduce the need to take regular, daily full backups.
LCR provides fast recovery with current data, as well as a
single-server solution for transaction log copying and
- Cluster continuous replication CCR
combines automatic management of redundancy and application-level
data replication. CCR is a solution that can be deployed without a
single point of failure in a single data center or between two data
centers. Transaction log replication is used to copy the databases
and maintain the concurrency of the data among cluster nodes. The
scheduled outage functionality in CCR is designed to make sure that
all log data on the active node is successfully copied to the
passive node. Therefore, scheduled outages do not result in loss of
data, even though replication occurs asynchronously.
Single Copy Clusters
A single copy cluster is a clustered mailbox server that uses shared storage to allow multiple servers to manage a single copy of the storage groups. This is similar to clustering in previous versions of Exchange Server. However, there are some significant changes and improvements that have been made.
In a single copy cluster, an Exchange 2007 mailbox server uses its own network identity, not the identity of any node in the cluster. This network identity is referred to as a clustered mailbox server. If the node running a clustered mailbox server experiences problems, the clustered mailbox server goes offline for a brief period until another node takes control of the clustered mailbox server and brings it online. This process is known as failover. The storage hosting the clustered mailbox server's storage groups and databases is hosted on shared storage that is available to each possible host node of the clustered mailbox server. As the failover happens, the storage associated with the clustered mailbox is logically disconnected from the failed node and placed under the control of the new host node of the clustered mailbox server.