Standard Scsi Bus Configuration - NEC HX4000 User Manual

A-2

Standard SCSI Bus Configuration

System Cabling
Your system is cabled using one on-board SCSI
controller and one PCI SCSI RAID controller expansion
card. The on-board Adaptec 7860 narrow SCSI
controller is used to control up to four removable media
peripherals (CD-ROM and tape drives). The two
channel PCI RAID controller expansion card is used to
control twelve additional hard disk 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 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.
The ultra wide SCSI interface cables for channel 0 and
channel 1 are connected to the SCSI connectors on the
PCI RAID Controller (see Figure A-1, U0 and U1).
These cables connect to the SCSI distribution panels
(see Figure A-1, K0 and K1) at the rear of the hard disk
drives. Termination for the hard disk drives is provided
on the SCSI distribution panels.
The onboard narrow SCSI controller also includes a
connector located at the rear of the system for
connecting external SCSI devices. 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 four SCSI devices in the system cabinet are
connected to the SCSI bus, only three 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.