Mac Pro and Xserve RAID Card: Boot Camp does not support RAID configurations
Boot Camp doesn't support any type of hardware or software RAID configuration.
This includes Microsoft Windows' built-in software RAID as well as any hardware RAID cards (such as Mac Pro RAID and Xserve RAID cards).
To partition your disk and install Windows using Boot Camp Assistant, the disk must be a single partition, formatted as a Mac OS X Extended (Journaled) volume. If you have already partitioned your disk using Disk Utility or some other utility, you cannot use Boot Camp Assistant until you restore your disk to a single-partition Mac OS X volume.
Boot Camp Assistant works only with internal disks. You cannot use Boot Camp Assistant to partition and install Windows on an external disk.