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Chapter A:
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SCSI cable length
The maximum allowable cable length for a low-voltage differential SCSI bus,
including all internal and external cables, is specified as follows:
■ If you have more than two devices on the LVD bus, the maximum
allowable length is 39 feet (12 meters).
■ If you are making a point-to-point connection (target and initiator only),
the maximum length is 82 feet (25 meters).
■ To determine the cable length of the bus, measure the lengths of all
external SCSI cables. Add those lengths together. To that sum, add 26.8
inches (68 centimeters) for the internal SCSI cable length.
SCSI terminator requirements
If the autoloader or the tape drive is the last device on the SCSI bus, you must
install an external, wide LVD terminator on the unused SCSI connector. Do not
use internal terminators to terminate the autoloader or the tape drive. We
recommend using a SCSI-3 type SE/LVD multi-mode terminator.
Important To comply with the safety and regulatory agency standards
for the autoloader, all SCSI cables you use with the
autoloader must be correctly shielded.
Important The autoloader and the tape drive are independent SCSI
devices on the same SCSI bus. As a result, when they are
connected to the initiator, there are a minimum of three
devices attached to the SCSI bus. Therefore, the
maximum allowable cable length is 39 feet (12 meters).
Important We recommend using active termination. Testing has
shown that older passive termination does not provide
rising edge transitions that are fast enough or clean
enough at fast SCSI speeds.