From Linux on Power wiki

How to setup hardware raid after installing OS

Use ipcronfig command. Discs are going to be formatted for Raid, so all data is lost afterwards.

1. run iprconfig
2. Select 2: Work with disk arrays
3. Select: 5. Format device for advanced function (522)
4. Select all disks you want use pressing 1, enter
5. confirm pressing c
6. Select 2: Create a disk array
7. Press 1 Create a disk array
8. Press 1 for each disk you are going to use, press enter
9. Select protection level (0, 10, 5)
10. Select stripe size (default for raid5 64k), press enter