Advantages of Cluster Continuous Replication over Single Copy Clusters
Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-09-12
Cluster continuous replication (CCR) in Microsoft Exchange Server 2007 provides several advantages over clustering in previous versions of Exchange Server and single copy clustering in Exchange 2007:
- No single point of failure CCR creates a clustered solution that uses a model of active and passive pairs. This model means that all key functionality or data has an active instance and one passive (backup) instance.
- No requirement for shared storage Storage in a CCR environment is not shared between the nodes in the failover cluster. This makes setup easier because storage does not need to be configured prior to forming the cluster. You can select between direct attached storage, storage area network (SAN), iSCSI, or other supported storage. For more information about supported storage solutions, see Planning Storage Configurations.
- Microsoft-provided solution that allows a single mailbox server to span two datacenters The cluster features in previous versions of Exchange Server required a third-party replication solution to enable site resiliency. In Exchange 2007, site resiliency is provided in the product.
- No specialized cluster validation required for hardware configuration Because CCR does not require shared storage, it is not necessary to select hardware from the Cluster category or Geographically Dispersed Cluster category in the Microsoft Windows Server Catalog. The only requirement is that the servers are listed as standalone servers in the Windows Server Catalog.
- Improved failover behavior Exchange 2007 failover behaviors take advantage of two completely independent copies of the log and database data. This design improves the overall recovery behavior and reduces the likelihood of recovery operations being blocked by the same failure.
- Simplified installation The Exchange 2007 installation experience has improved over previous releases. The clustered mailbox server installation has been unified with the stand-alone mailbox server installation. As a result, administrators have an experience that is consistent across both environments. Because there is no requirement for shared storage, installation is further simplified.
- Improved management experience The management experience has been improved by hiding cluster-specific administration under associated Mailbox server operations. For example, storage group configuration within Exchange does all the necessary updates to the high availability infrastructure used to manage the cluster. The management experience is also improved because there is no requirement for shared storage.
- Ability of offload backup workload CCR creates a second copy of databases on a passive node. The passive node can be used to offload the effect of doing regular backups. For example, by doing backups on the passive node, the backup window can be extended and the I/O load is no longer on the active node. Backups are supported for both production and copy storage groups and databases using an Exchange-aware Volume Shadow Copy Service (VSS)-based solution, such as Microsoft System Center Data Protection Manager 2007. Streaming backups are only supported from the active node. Exchange-aware restores to the active copy can either be done using streaming or VSS backup solutions.