Installing Drives 7-11
Although SCSI devices are installed essentially the same
way as other devices, their configuration requirements
are different.
SCSI Configuration Guidelines
For details on configuring your SCSI subsystem, refer to
the documentation that came with your SCSI devices
and/or your host adapter card. The following subsections
offer some general guidelines.
SCSI ID Numbers
Each device attached to a SCSI host adapter card, as well
as the card itself, must have a unique SCSI identification
(ID) number from 0 to 7. When SCSI devices are shipped
from Dell, the default SCSI ID numbers are assigned as
follows:
•A SCSI host adapter card is configured as SCSI ID
7.
•A SCSI tape drive or digital audio tape (DAT) drive
is configured as SCSI ID 6.
•A SCSI CD-ROM drive is configured as SCSI ID 5.
•SCSI hard-disk drives are usually configured as
SCSI ID 0. (The drive used to boot your system
should always be configured as SCSI ID 0.)
NOTE: There is no requirement that SCSI ID numbers be
assigned sequentially or that devices be attached to the
cable in order by ID number.
SCSI Cable and SCSI Termination
The type of cabling you receive with your SCSI device
depends on the type of device you are installing.
•If you are installing an internal narrow SCSI device
(such as a CD-ROM drive or tape drive), you have a
50-pin internal SCSI cable as shown in Figure 7-14.
One end of this cable attaches to the SCSI host
adapter. The three connectors on the other end of the
cable are used for attaching up to three narrow SCSI
devices installed in the externally accessible drive
bays.

Figure 7-14. Internal SCSI Cable

•If you are installing an internal wide SCSI device
(such as a wide SCSI hard-disk drive), you have a
68-pin internal SCSI cable as shown in Figure 7-14.
One end of this cable attaches to the SCSI host
adapter and the two connectors on the other end of
the cable are used for attaching up to two SCSI hard-
disk drives installed in the hard-disk drive bracket.
•If you are installing an external SCSI device, you
have a shielded external cable that connects to the
external SCSI connector on the SCSI host adapter
card. You have a separate power cable to connect the
SCSI device to an AC power source.
Before installing SCSI devices in your computer, you
may need to configure the termination on your SCSI
device(s). Both types of internal SCSI cables contain ter-
minators on the device end of the cables, so the devices
connected to these cables must have termination dis-
abled. External SCSI cables do not have terminators, so
termination must be enabled on the SCSI device itself.
If you are installing only internal SCSI devices, verify that
termination is enabled on the SCSI host adapter and dis-
abled for all other internal SCSI devices. If you are installing
both internal and external SCSI devices, verify that termina-
68-pin SCSI cable
(to hard-disk drive)
50-pin SCSI
cable (to device in
externally accessible
drive bay)