DrakX will first detect any IDE devices present in your computer. It will also scan for one or more PCI SCSI cards on your system. If a SCSI card is found, DrakX will automatically install the appropriate driver.
Because hardware detection is not foolproof, DrakX may fail in detecting your hard drives. If so, you'll have to specify your hardware by hand.
If you had to manually specify your PCI SCSI adapter, DrakX will ask if you want to configure options for it. You should allow DrakX to probe the hardware for the card-specific options which are needed to initialize the adapter. Most of the time, DrakX will get through this step without any issues.
If DrakX is not able to probe for the options to automatically determine which parameters need to be passed to the hardware, you'll need to manually configure the driver.