your SCSI drive is not installed correctly or isn't loaded.
During the installation of NT, the system ask if you have any 3rd party software/hardware to add...you were suppose to press S to specify what you have and use the drivers that came with the CP disks/CD-ROMs
If this is post installation and you're getting this, then the driver is corrupted and its time repair NT; hopefully, you have an ERD...otherwise you're starting over.