To set up a MegaRAID with Raid 5 on an Xserve follow these steps:
1. Boot the server from OSX Server CD
2. Open the Terminal application
3. Type in the command
megaraid -create auto
4. Close the Terminal application
5. Open the Disk Utility application
6. Create a new partition on the new RAID drive with the Disk Utility application
7. Reinstall the operating system with the Mac OS X server CD or DVD
8. Done