Operation Manual

34 Netra t 1400/1405 Installation and User’s Guide • September 1999
■ Support for up to seven internal SCSI devices (including the host adapter):
■ Fast-20 SCSI disk drive target 0 (left-most drive slot)
■ Fast-20 SCSI disk drive target 1
■ Fast-20 SCSI disk drive target 2
■ Fast-20 SCSI disk drive target 3 (right-most drive slot)
■ Fast-10 SCSI removable media device target 4
■ Fast-10 SCSI removable media device target 6
■ Support for external 8-bit and 16-bit SCSI devices via 68-pin SCSI connector
mounted on an adapter board
SCSI Cabling and Configuration
The SCSI-3 Fast-20 (UltraSCSI) specification requires that the external SCSI bus
length be limited to 3m (10ft) for less than five devices (internal and external), and
1.5m (5ft) for five to eight devices. When SCSI-3 and SCSI-2 devices are connected to
the Netra t 1400/1405 system SCSI bus, the system enables each device to operate at
its respective data transfer rate. The last external SCSI device in a daisy-chain must
be terminated internally (active termination) or with an external terminator
according to Forced-Perfect Termination (FPT) technology.
SCSI Cabling Procedure
1. Count the number of SCSI devices on the system SCSI bus. Be sure to count the
host adapter as a SCSI device.
2. Determine the total SCSI bus length.
*The maximum numberofsingle-ended/differentialSCSI devices is16.
TABLE 4-6
Determining SCSI Bus Length
SCSI Implementation Bus Width
DataTransfer
Rate, Mb/s
Number of
Devices
SCSI
Bus Length
SCSI-2, Fast 8 bits 10 1–8 6.0m
SCSI-2, Fast/Wide 16 bits 20 1–8 6.0m
SCSI-3 Parallel Interface, Fast-20 Wide
(UltraSCSI) (WideUltra)
16 bits 40 1–4 3.0m
SCSI-3 Parallel Interface, Fast-20 Wide
(UltraSCSI) (WideUltra)
16 bits 40 5–8
*
1.5m
LW3User.book Page 34 Wednesday, November 10, 1999 9:00 AM