IBM HANDBOOK 260 - Manual (Page 124)

106 RS/6000 43P 7043 Models 150 and 260 Handbook
The following describes the SCSI cabling of the two PCI SCSI adapters
supported by the Model 150 and 260 entry workstation and workgroup
servers:
• PCI Single-Ended Ultra SCSI Adapter (# 6206)
• PCI Differential Ultra SCSI Adapter (# 6207)
4.3.1 General SCSI Cabling Considerations
Before describing SCSI cabling features, it is necessary to understand the
following primary specifications of SCSI technology:
• Default SCSI cable routing
• Maximum SCSI bus length
• SCSI terminators
• SCSI device addresses
• SCSI bus width
4.3.1.1 Default SCSI Cable Routing
SCSI IDs for the storage devices are defined by the location in which they are
installed. The standard SCSI cable is used for all combinations. SCSI
termination is done on the system planar. Termination setting of all internal
SCSI devices must be set to OFF.
4.3.1.2 SCSI Bus Length
SCSI bus length is defined as the distance between terminators at either end
of a SCSI bus. The SCSI specifications allow the following maximum bus
length for each SCSI bus:
• SCSI-II Single Ended: 6 meters (20 feet)
• SCSI-II Fast/Wide Single Ended: 3 meters (10 feet)
• SCSI-II Fast/Wide Differential: 25 meters (80 feet)
For configurations using both internal and external cabling, length restrictions
apply to the length from the end of the internal cable to the terminator on the
last device on the external bus.
Refer to the publication IBM RS/6000 Adapters, Devices and Cables
information for Multiple Bus Systems, SA38-0516, for specific SCSI cabling
information.
Note