Installation guide

What is the SCSI bus?
A-2 FlashPoint™ LT BT-930 User’s Manual
• SCSI-3 adds more features including Ultra SCSI, SCAM, optional P-
cable, the Wide SCSI bus specification that defines an extended
number of devices, support for fiber channel hardware, and a serial
channel interface. It also allows transfer rates of 20 megabytes per
second.
What is the SCSI bus?
A SCSI bus is one or more SCSI peripheral devices and a host adapter
connected together by cables in a daisy chain configuration. The SCSI bus
may include both internal and external devices on one bus.
• A Narrow SCSI bus may have up to eight devices. The host adapter
counts as one device.
• Wide SCSI supports up to 16 devices. Note, however, that Wide SCSI
is not supported by the FlashPoint LT host adapter.
What are the SCSI bus length limitations?
The SCSI bus maximum length is determined by the data transfer rate and
the number of devices in the configuration. Table A-1 lists the data transfer
rates, the maximum number of devices and the maximum allowable cable
lengths for each.
Remember when measuring the length of the SCSI bus, you must include all
the connecting cables including the internal cable if it is used to connect
internal devices.
Table A-1. Maximum SCSI Bus Configuration Limits (Narrow Only)
SCSI Type Data Transfer Rate
(in megabytes per
second)
Maximum
Number of
Devices
Maximum
Cable Length
SCSI-2 5 or less 8 6 meters (19.7 feet)
SCSI-2 10 8 3 meters (9.8 feet)
Ultra SCSI 20 4 3 meters (9.8 feet)
Ultra SCSI 20 8 1.5 meters (4.9 feet)