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138 Appendix C
SCSI Connections
SCSI Bus Length Constraints
SCSI Bus Length Constraints
This section discusses SCSI bus lengths constraints for the SE and LVD SCSI devices.
SE SCSI Bus Length
When the J6000 external SCSI bus is used in single-ended (SE) mode, the maximum cable
length for an SE SCSI bus is 3 meters.
NOTE
When calculating the total SE SCSI cable/bus/trace length used externally,
remember to account for cables connecting external devices together as well
as the bus length internal to those devices.
There are two total cable length specifications you need to consider when dealing with an
SE SCSI bus on a workstation. Note that these specifications are based on the requirement
that the SCSI device being connected to the SE SCSI bus does not exceed the maximum
capacitance of 25 picofarads (pF). Please check with the vendor of the SCSI device if you
are not sure of the device’s maximum capacitance.
The total cable length specifications are as follows:
• For a total of one to four devices being connected to the SE SCSI bus, the total length of
cable used should not exceed 3.0 meters.
• For a total of five to eight devices being connected to the SE SCSI bus, the total length
of cable used should not exceed 1.5 meters.
NOTE
The computer is counted as one of the devices, and the internal length of its
cabling is 0.15 meters. This length needs to be considered in determining the
total cable length.
LVD SCSI Bus Length
When the J6000 external SCSI bus is used in low voltage differential (LVD) mode, the
maximum cable length for a LVD SCSI bus is 12 meters..
NOTE
When calculating the total LVD SCSI cable/bus/trace length used externally,
remember to account for cables connecting external devices together as well
as the bus length internal to those devices.