2.Configure all SCSI devices to supply TermPWR.

3.Set proper target IDs (TIDs) for each SCSI device. The cable length can be up to 20 m.

6.2.6.1Cable Suggestions

System throughput problems can occur if SCSI cable use is not maximized. Here are some cabling guidelines:

￿You can use cables up to 12 meters for LVD devices.

￿For single-ended SCSI devices, use the shortest SCSI cables.

￿Use active termination.

￿Avoid clustering the cable nodes.

￿Cable stub length should be no more than 0.1 meter (4 inches).

￿Route SCSI cables carefully.

￿Use high impedance cables.

￿Use flat cables for inside the enclosure, and round, shielded cables for outside of the enclosure.

￿Ribbon cables have fairly good cross-talk rejection characteristics.

6.2.7Step 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-ROM 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. The MegaRAID SCSI 320-1 controller automatically occupies TID 7 in the SCSI channel. Eight-bit SCSI devices can only use the TIDs from 0 to 6. 16-bit devices can use the TIDs from 0 to 15. The arbitration priority for a SCSI device depends on its TID.

Table 6.5 shows the relative priority of each Target ID:

Table 6.5 Priority of Target IDs

Priority

Highest

 

 

Lowest

 

 

 

 

 

 

 

 

TID

7

6

5 ... 2

1

0 15 14 ... 9

8

 

 

 

 

 

 

 

6-14Hardware Installation

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