You do see the Rockstor splash screen, correct? If you do, then you can remove the ks directive. See this thread for more info: Install on HP DL360 G5 fails to detect hardware raid [solved]
If you are able to proceed without the ks=… parameter, great. But make sure you go with BTRFS partitioning scheme. LVM may be the default and you need to change that to BTRFS.