F i g u r e 1 0 - 3 . E x a mp l e o f Te r m i n at i o n

SCSI

Terminator

Termination on Controller

SCSI Devices

Enabled

(Termination Disabled on Both)

For a disk array, set SCSI bus termination so that removing or adding a SCSI device does not disturb termination. An easy way to do this is to connect the PERC 3/QC card to one end of the SCSI cable and to connect an external terminator module at the other end of the cable. The connectors between the two ends can connect SCSI devices. Disable termination on the SCSI devices. See the manual for each SCSI device to disable termination.

SCSI Termination

The SCSI bus is an electrical transmission line and it must be terminated properly to minimize reflections and losses. You complete the SCSI bus by setting termination at both ends.

You can let PERC 3/QC automatically provide SCSI termination at one end of the SCSI bus. You can terminate the other end of the SCSI bus by attaching an external SCSI terminator module to the end of the cable or by attaching a SCSI device that internally terminates the SCSI bus at the end of the SCSI channel.

Selecting a Terminator

Use standard external SCSI terminators on a SCSI channel operating at 10 MB/s or higher synchronous data transfer.

PERC 3/QC Hardware Installation

141

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Dell manual G u r e 1 0 3 . E x a mp l e o f Te r m i n at i o n, 141