Seagate CHEETAH 18 ST118202LW/LC - Handbuch (Seite 24)

22 Cheetah 18 Installation Guide, Rev. A
Drive termination
If you are installing a Cheetah drive in a system that has other
SCSI devices installed, terminate only the end devices on the
SCSI chain. A SCSI “device” is any disc drive, scanner, tape
backup unit, or other piece of hardware connected to your sys-
tem using the SCSI bus.
Note. Use active (ANSI SCSI-2 Alternative 2) single-ended ter-
minators when terminating a bus operating in single-
ended mode. Use SPI-2-compliant active low voltage dif-
ferential terminators when terminating a SCSI Ultra2 bus
operating in LVD mode.
The top example in Figure 2 shows an internal hard disc at one
end of the SCSI bus with the SCSI controller at the other end
(both are terminated). The bottom example shows two additional
SCSI devices connected externally—this means the SCSI con-
troller is no longer on the end of the SCSI chain and should not
be terminated.
Note. Some controllers prefer to remain terminated even if they
are in the middle of the chain. Also, some controllers treat
the internal and external chains as separate logical
buses. This means you may need to terminate both the
first and last devices on both logical buses to achieve
proper termination. If necessary, refer to your system or
controller documentation to see how this is handled in
your particular system.
These drives do not have on-board terminators, so you must ter-
minate external to the drive when termination is required. For
ST118202LC drives, this is normally accomplished by terminat-