N/APosted on - 10/26/2011
I am planning to upgrade my Exchange Server 2003/2007 to 2010. Can I still use Single Copy Cluster (SCC), Local Continuous Replication (LCR), Stand-by Continuous Replication (SCR) and also Cluster Continuous Replication (CCR)? I heard that in Exchange 2010, these high availability options were replaced by DAGs or the Database Availability Groups. If so, what are the benefits of using DAG in Exchange 2010?
The high availability options for Mailbox Databases
Hi Maddison Harvey,
Although Exchange 2007 provided a variety of replication and clustering options, including LCR, single-copy clusters and clustered Mailbox servers, but they proved a challenge to the administrator for their implementation. Like each approach to HA was managed in a different way, each mailbox servers in a clusters used shared storage, forcing the administrator to configure windows fail over clustering which a really tedious task.
In Exchange 2010 server, the high availability is integrated to its core architecture, providing service availability, data availability, and automatic recovery. This negates the requirement of different HA used previously. This is called DAG (Database Availability Group)
The automatic failover and recovery is available in DAG on the Database level instead of server level without requirement of clusters when multiple mailbox servers are deployed with copies of multiple mailbox databases. DAGs can be extended to multiple active directory sites and related architectural changes to Mailbox servers enable a single mailbox database to move between Active Directory sites, resulting single mailbox database in one AD site can failover to another AD site.
I suggest that you go through the article about Exchange 2010 High Availability by Neil Hobson