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

68MegaRAID Enterprise 1600 Hardware Guide