Standard SCSI Bus Configuration
Your system is cabled using the two on-board SCSI controllers. The on-board Adaptec 7880 ultra wide SCSI controller is used to control the six hard disk drives and the on-board Adaptec 7860 narrow SCSI controller is used to control up to three removable media peripherals (CD-ROM and tape drives). A 3 1/2-inch diskette drive is installed in all systems and interfaces separately to the system board. Figure A-1 is a diagram of the standard SCSI cabling and Figure A-2 illustrates the internal cable routing for this configuration.
The narrow SCSI interface cable is connected to the SCSI connector below the ultra wide SCSI connector on the top edge of the system board (see Figure A-1, D). This cable connects to the rear of the SCSI removable media peripherals (if present). The last drive on the daisy chain cable must have it’s internal SCSI terminators installed. If your server doesn’t have any removable media peripherals, the cable is not used and the narrow SCSI controller is terminated using the SCSI termination resistors (see Figure A-1, E).
The ultra wide SCSI interface cable is connected to the SCSI connector on the top edge of the system board (see Figure A-1, J). This cable connects to the SCSI distribution panel at rear of the hard disk drives. Termination for the hard disk drives is provided on the SCSI distribution panel.
The onboard narrow SCSI controller also includes a connector located at the rear of the system for connecting external SCSI devices (Figure A-1,D). Three important rules must be followed if you connect external narrow SCSI devices.
■A maximum of seven narrow SCSI devices may be connected to the onboard SCSI controller. For example if three SCSI devices in the system cabinet are connected to the SCSI bus, only four external narrow SCSI devices can be connected.
■The maximum cable length for all narrow devices connected to the controller is 1 meter (39 inches).
■The last external narrow SCSI device must be terminated. Active termination is recommended.
