Dell OptiPlex G1 - Manual (Page 86)

Installing Drives: Dell OptiPlex GX1 Low-Profile Managed PC Systems
file:///C|/infodev/2013/eDoc/OpGX1/SQRG/drives.htm[2/21/2013 11:53:04 AM]
Installing SCSI Devices
To use SCSI devices in your Dell computer, you must have a SCSI host adapter card, which comes with its
own SCSI cable. This cable can be used to attach a variety of SCSI devices (hard-disk drives, tape drives,
and so on). The SCSI host adapter configures the devices attached to it as one subsystem—not as
independent devices.
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 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 (typically the default ID for a host adapter card).
A SCSI tape drive or digital audio tape (DAT) drive is configured as SCSI ID 6 (typically the default ID
number for a tape drive).
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 internal SCSI devices (such as CD-ROM, hard-disk, or tape drives), you have
internal SCSI cables as shown in
Figure 14 . Narrow SCSI devices use a 50-pin cable; wide SCSI
devices use a 68-pin SCSI cable. One end of each cable attaches to the SCSI host adapter. The
connectors on the other end of the cable attach to the internal SCSI devices.
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 terminators on the device end of the cables, so the
devices connected to these cables must have termination disabled (see Figure 14). External SCSI cables do
not have terminators, so termination must be enabled on the SCSI device itself.
Figure 14. Internal SCSI Cables