Sil 3114 and two disk

Hi, I have a Gygabite MotherBoard with Sil3114 Raid Chipset and 2 HD. Into the bios of Sil 3114 I have set one Raid0 so when I boot the PC (before the boot manager menu) I see the text: "Sil0 138GB". Ok, it is correct. Now I want to install Suse 9.3 Pro, I boot from DVD and I see 2 HDx73GB and not HD 1x138GB. Why ? This is correct ? Tnx in advance for all and sorry for my bad english. M.