114 PERC 3/SC Hardware Installation
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Perform the following steps to connect SCSI devices:
1 Disable termination on any SCSI device that does not sit at the end of
the SCSI bus.
2 Configure all SCSI devices to supply termination power (TermPWR.)
3 Set proper target IDs (TIDs) for all SCSI devices.
Cable Suggestions
System throughput problems can occur if SCSI cable use is not maximized.
You sh ou ld:
• Use cables up to 12 meters for LVD devices.
• For single-ended SCSI devices, use the shortest SCSI cables (no more
than 3 meters for Fast SCSI, no more than 1.5 meters for an 8-drive
Ultra SCSI system, and no more than 3 meters for a 6-drive Ultra SCSI
system.)
• Use active termination.
• Avoid clustering the cable nodes.
• Note that cable stub length should be no more than 0.1 meter (4
inches.)
• Route SCSI cables carefully.
• Use high impedance cables.
• Do not mix cable types. (Choose either flat or rounded and shielded or
non-shielded.)
• Note that ribbon cables have fairly good cross-talk rejection
characteristics.
Step 7—Set Target IDs
Set target identifiers (TIDs) on the SCSI devices. Each device in a specific
SCSI channel must have a unique TID in that channel. Non-disk devices
(CD or tapes) should have unique SCSI IDs regardless of the channel where
they are connected. See the documentation for each SCSI device to set the
TIDs.
