Asus DSBF-DM/SAS - Manual (Page 132)

5-22 Chapter 5: RAID configuration
5. When prompted, press the <SpaceBar> to select Yes from the Initialize?
dialog box, then press <Enter>.
6. A progress bar appears on screen. If desired, press <Esc> to abort
initialization.
7. When initialization is completed, press <Esc>.