Installation

SCSI Cabling

The controller supports two Ultra 160 SCSI channels which can support up to 30 SCSI devices, (15 per channel).

LVD Mode

The controller supports Ultra 160 SCSI with LVD. If all drives attached to a controller drive channel support Ultra 160 SCSI with LVD, then that channel will operate at a maximum of 160MB/s burst speed. This setup allows a maximum SCSI bus length of up to 12 meters.

☛Note

The SCSI bus length can be extended up to 25 meters if only the controller and one drive are on the bus in a point-to-point configuration.

Single-ended Mode

If any device on the channel does not have LVD electrical characteristics, the channel will revert to single-ended operation mode. The SCSI bus lengths will then be limited to the single-ended bus lengths shown in Table 2-5.

Table 2-5. SCSI Formats and Bus Lengths

SCSI Trade Association

Bus

Bus

Max. Bus Length, Meters

Max. Device

(STA) Terms

Speed,

Width,

 

 

Support

Single-ended

Low-Voltage

 

MB/Sec,

Bits

(Including

 

 

Differential

 

Max.

 

 

Controller)

 

 

 

 

 

 

 

 

 

 

SCSI-1

5

8

6

-

8

 

 

 

 

 

 

Fast SCSI

10

8

3

-

8

 

 

 

 

 

 

Fast Wide SCSI

20

16

3

-

16

 

 

 

 

 

 

Ultra SCSI

20

8

1.5

-

8

 

 

 

 

 

 

Ultra SCSI

20

8

3

-

4

 

 

 

 

 

 

Wide Ultra SCSI

40

16

-

-

16*

 

 

 

 

 

 

Wide Ultra SCSI

40

16

1.5

-

8

 

 

 

 

 

 

Wide Ultra SCSI

40

16

3

-

4

 

 

 

 

 

 

Ultra2 SCSI

40

8

Not Defined

12†

8

 

 

 

 

 

 

Wide Ultra2 SCSI

80

16

Not Defined

12†

16

 

 

 

 

 

 

Ultra 160 SCSI

160

16

Not Defined

12†

16

 

 

 

 

 

 

*The Maximum number of devices allowed on a Wide Ultra SCSI bus is 8, unless bus extender technology is used.

†This length can be extended to 25 meters if there are only 2 devices (e.g., the controller and one drive) on the bus in a point-to-point configuration.

Manual No. 775051

2-17