I believe you're using IT/IR RAID which support IM/IME. IME volumes can have three to ten disks.
You can have up to two volumes on the same IT/IR controller.
If you need more volumes or more RAID level support, add hardware RAID key and RAID memory. For more information, please check http://www.intel.com/support/motherboards/server/sb/cs-030410.htm.
Thanks for the info. I will have a look at that url.