In January 2006, Dave Thompson, corporate vice president of the division responsible for Exchange Server at Microsoft, hit the road on a press tour to tout the improvements planned for Exchange Server 2007. One thing he mentioned was striking: Exchange 2007 was intended to reduce the cost and complexity of providing high availability for messaging services. This sounded like an excellent idea, but Thompson’s press tour was relatively short on details. Now that Exchange 2007 is available, it’s time to see what the new high-availability features are and how they might affect your deployment plans. Your organization could benefit from adding redundancy with your server roles or from the new replication features, local continuous replication (LCR) and cluster continuous replication (CCR).
Clustering Changes
Let’s start with clustering, arguably the most complicated (and least understood) of Exchange 2007’s high-availability features. First, there are some new buzzwords for describing clusters. A traditional shared-storage cluster is now referred to in Exchange documentation as a single copy cluster (SSC). That’s because it keeps only a single copy of each data item, which can be owned by only one node in the cluster at a time. However, the new cluster mode, CCR, lets you operate shared-nothing clusters, where there are no data items and no shared storage. . . .
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