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1-8 Dell PowerEdge 4200 Systems Service Manual
Controller host adapter card, the SCSI backplane board allows you to remove
and insert hard-disk drives without shutting down the system. External hard-
disk drives are not supported by the built-in SCSI controller.
A built-in Adaptec 7860 Ultra/Narrow SCSI controller provides a SCSI inter-
face via a 50-pin connector to the CD-ROM drive in the externally accessible
drive bay and to any other SCSI drives installed in the other two bays.
SCSI Hard-Disk Drives
Six internally accessible hot-pluggable hard-disk drive bays are located under
the externally accessible drive bays at the front of the computer (see Figure 1-
4). These bays can contain up to six 1- to 1.6-inch-high SCSI hard-disk drives
(either Ultra/Wide or Ultra/Narrow).
NOTE: The externally accessible drive bays at the front of the computer are
normally used for diskette drives, CD-ROM drives, and/or tape drives. Hard-
disk drives should be installed in the SCSI hard-disk drive bays. For detailed
information about installing externally accessible drives, see Chapter 4 of this
manual.
SCSI Configuration Guidelines
Although SCSI devices are installed essentially the same way as other devices,
their configuration requirements are different. To configure your SCSI sub-
system, follow the general guidelines offered in the following subsections.
SCSI ID Numbers
Each device attached to the 7860 Ultra/Narrow SCSI host adapter must have a
unique SCSI ID number from 0 to 7.
When Narrow SCSI devices are shipped from Dell, the default SCSI ID num-
bers are assigned as follows:
•
The computer’s built-in Ultra/Narrow SCSI host adapter is configured
through the BIOS as SCSI ID 7.
•
A SCSI CD-ROM drive (installed in an externally accessible drive bay) is
configured as SCSI ID 5.
•
A SCSI tape drive (if installed) is configured as SCSI ID 6.
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.
Devices attached to the Ultra/Wide SCSI host adapter need no ID settings or ter-
mination; ID settings and termination are handled automatically by the SCSI
backplane.
Device Termination
SCSI logic requires that termination be enabled for the two devices at opposite
ends of the SCSI chain and disabled for all devices in between. Therefore,