MegaRAID Enterprise 1600 Hardware Guide
68
Step 10 Connect SCSI Cables,
Continued
J13 A and B External Connector
J13 is a dual 68-pin ultra-high density external SCSI connectors. It is on the
MegaRAID mounting bracket.
Connect SCSI Devices
When connecting SCSI devices:
Action Description
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 TermPWR.
3 Set proper target IDs (TIDs) for all SCSI devices.
4 Distribute SCSI devices evenly across the SCSI channels for optimum
performance.
5 The cable length should not exceed three meters for Fast SCSI (10
MB/s) devices or 1.5 meters for Ultra SCSI devices.
6 The cable length should not exceed six meters for non-Fast SCSI
devices.
7 Try to connect all non-disk SCSI devices to a SCSI channel that has no
SCSI disk drives connected to it.
Cable Suggestions
System throughput problems can occur if SCSI cable use is not maximized. You should:
• use the shortest SCSI cables (in SE mode, 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)
• LVD mode cable lengths should be no more than 25 meters with two devices and no more
than 12 meters with eight devices
• use active termination
• avoid clustering the stubs
• 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)
• ribbon cables have fairly good cross-talk rejection characteristics
