Zenith Data Systems MT2000 - Manual (Page 173)

A-2
System Cabling
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.