Microsoft published a very interesting whitepaper about their use of Exchange Server 2007 and Cluster Continuous Replication (CCR). I was surprised to learn that they use DAS instead of a SAN-based solution. When you think of it, it makes sense because it eliminates some complexity and dramatically lowers the implementation costs. A big advantage of that design is that it avoids what they call hot-spot contention when another workload is using the same spindles as Exchange Server 2007.

All in all a very interesting read! You can find it here.