Good morning. For the array to function, you have followed the correct procedure and it should be set to RAID.   The array will continue to initialize and you should be able to install the OS while it initializes in the background.  Regards, 
Hi. I'm now installing R420 server, and I have one question about physical disk mode. I'm entered BIOS, and changed SATA mode from "AHCI" to "RAID". Then I removed preinstalled RAID5 Virtual Disk, and vreated RAID10 Virtual disk. Now array is initializing. My question is: is it right switching SATA to "RAID" mode? May be, switching it back to "AHCI" mode will be more correct?
Dell PowerEdge R420 - setting up RAID10 array