E20-818 Question #111: Real Exam Question with Answer & Explanation

A customer is migrating their Microsoft Exchange 2007 server from a NAS back end to a new Symmetrix V-Max SE array. Perfmon was used to create a log view of an average day's activity against the database LUN of the busiest datastore in the Exchange environment. This will serve as the performance benchmark for all other database LUNs. There are an additional four mailbox databases on this server. How many RAID 1-protected 15k rpm spindles are required to satisfy the performance needs of the customer for all the mailbox databases on this server?