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Scsi cabling guidelines, Cable lengths, Scsi cabling guidelines -10 – Avago Technologies eXtremeRAID 2000 User Manual

Page 32: Cable lengths -10

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SCSI Cabling Guidelines

2-10

eXtremeRAID 2000 Installation Guide

SCSI Cabling Guidelines

The eXtremeRAID 2000 supports up to four Ultra 160 SCSI channels. Each
channel supports up to 15 devices.

Cable Lengths

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 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 2-2.

* 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 (the controller and one

drive) on the bus in a point-to-point configuration.

Table 2-2. Supported SCSI Formats and Bus Lengths

SCSI Trade Association
(STA) Terms

Bus

Speed,

MB/Sec,

Max.

Bus

Width,

Bits

Max. Bus Length, Meters

Max. Device

Support

(Including

Controller)

Single-Ended

Low-Voltage

Differential

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