This message was posted on behalf of Intel Corporation
You can try this suggestion;
1. Set both disks to Non-RAID from Ctrl-I menu.
2. Disconnect one of the disks.
3. Install the operating system on the connected disk.
4. Make sure the operating system is working.
5. Set everything back from the IRST, meaning creating a new RAID volume with operating system you want run.
Let me know if that works.