Hi Bobc – RAID10 is definitely what’s recommended for Exchange. Have a look at: http://msexchangeteam.com/archive/2004/10/11/240868.aspx for more information.
look at the IO’s of the data
Raid five has 5 disk writes to raid 1 having 2.
Raid 1 is faster for writes and offers better protection as well and resilience in event of failure.
Raid 5 is a reasonably priced resilience model based of reduced performance in the event of a disk failure.
Raid 1 is expensive and raid 5 is cheaper but raid 1 offers better performance at a higher cost