Installing Scsi Devices in the External Bays

Most interface connectors are keyed for correct insertion; that is, a notch or a raised tab on one connector matches a tab or notch on the other connector. Keying ensures that the pin-1 wire in the cable (indicated by the colored strip along one edge of the cable) goes to the pin-1 ends of the connectors on both ends.

CAUTION: When connecting an interface cable, do not reverse the interface cable (do not place the colored strip away from pin 1 of the connector). Reversing the cable prevents the drive from oper- ating and could damage the controller, the drive, or both.

DC Power Cables

Each drive in the external drive bays must connect to a

4-wire DC power cable from the system power supply or power-supply paralleling board. The connectors on this cable are labeled “FD1,” “FD2,” “FD3,” “FD4,” and “FD5.” Connectors FD1 through FD4 are used for

5.25-inch devices, whereas connector FD5 is used for the standard 3.5-inch diskette drive. Before connecting a drive to a power cable, refer to Figure 9-5 to identify the correct cable connector to use for the drive.

system board connector

5.25-inch drive	3.5-inch drive
connector	connector

Figure 9-5. DC Power Cable Connectors

Installing SCSI Devices in the External Bays

SCSI devices in the external drive bay (such as CD-ROM drives and tape drives) are controlled by the Ultra/Wide SCSI controller on the system board.

SCSI Configuration Information

Although SCSI devices are installed essentially the same way as other devices, their configuration requirements are different. To configure SCSI devices installed in the external bays, follow the guidelines in the following subsections.

SCSI ID Numbers

Each device attached to the Ultra/Wide SCSI host adapter 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:

•The computer’s built-in Ultra/Wide SCSI host adapter is configured through the basic input/output system (BIOS) as SCSI ID 7.

•A SCSI tape drive is configured as SCSI ID 6 (the default ID number for a tape drive).

•A SCSI CD-ROM drive is usually configured as SCSI ID 5.

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.

Device Termination

SCSI logic requires that the two devices at opposite ends of the SCSI chain be terminated and that all devices in between be unterminated.

Before installing SCSI devices in the computer, you must configure the terminators on the SCSI device(s) to con- form to the following guidelines:

•A single SCSI device (such as the standard CD-ROM drive) is terminated.

9-4 Dell PowerEdge 6100/200 System Installation and Troubleshooting Guide