SCSI-2 drives do not require a format.dat entry. The format utility automatically configures the SCSI-2 drivers if the drives are powered on during a reconfiguration boot. For step-by-step instructions on configuring a SCSI disk drive automatically, see How to Automatically Configure a SCSI Drive.
If your disk is unrecognized, use a text editor to create an entry in format.dat for the disk. You need to gather all the pertinent technical specifications about the disk and its controller before you start. This information should have been provided with the disk. If not, contact the disk manufacturer or your supplier.