3 scsi concepts – OpenEye GraniteRack 3U User Manual

Page 16

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Introduction

1-10

1.3 SCSI Concepts

Before configuring the subsystem, you must first understand some basic

SCSI concepts so that the subsystem and SCSI devices will function

properly.

1.3.1 Multiple SCSI Format Support

The subsystem support the SCSI interface standards listed below. Note that

the data bit and cable length restrictions must be followed.

SCSI Type

SCSI-1
Fast SCSI
Fast Wide SCSI
Ultra SCSI
Ultra Wide SCSI
Ultra 2 SCSI
Ultra 2 Wide SCSI
Ultra 160 Wide LVD
Ultra 320 LVD

Data Bit

8 Bits
8 Bits
16 Bits
8 Bits
16 Bits

8 Bits

16 Bits

16 Bits
16 Bits

Data Rate

5 MB/Sec
10 MB/Sec
20 MB/Sec
20 MB/Sec
40 MB/Sec
40 MB/Sec
80 MB/Sec
160MB/Sec
320MB/Sec

Cable Length

6 m
3 m
3 m
1.5 m
1.5 m
12 m
12 m

12 m
12 m

1.3.2 Host SCSI ID Selection

A SCSI ID is an identifier assigned to SCSI devices which enables them to

communicate with a computer when they are attached to a host adapter via

the SCSI bus. Each SCSI device, and the host adapter itself, must have a

SCSI ID number (Ultra 320 Wide SCSI = 0 to 15). The ID defines each SCSI

device on the SCSI bus. If there are more than one SCSI adapter in the Host

subsystem, each adapter forms a separate SCSI bus. SCSI IDs can be re-

used as long as the ID is assigned to a device on a separate SCSI bus.

Refer to the documentation that came with your peripheral device to deter-

mine the ID and how to change it. The subsystem must be assigned a

unique SCSI ID ranging from 0 to 15 for the Ultra 320 LVD SCSI host system.

The default value is ID 0.

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