This white paper describes a tested and validated storage solution for a 3000 mailbox Exchange 2007 environment with Single Copy Cluster (SCC) in a high availability clustering mechanism based on the Microsoft Cluster Service (MSCS) shared storage. It requires an active and a passive set of Exchange Mailbox server nodes sharing the mailbox databases. During normal operations, mail clients access the primary (active) server. In the event of a primary node failure, the passive or standby node will take over the functionality of the failed node. This process is termed as a fail-over and these types of clusters are also popularly termed as fail-over clusters. Compared with previous versions, Exchange Server 2007 provides improved deployment setup and management experience with this clustering model.