Ultra ATA Drive Guidelines and Features

4.3.1 Device Classes

In order to determine the best drive attach sequence, ATA/ATAPI drives are segregated into four different classes based upon the bandwidth demands they place on an ATA controller. The most demanding devices are in Class 1 and the least demanding are in Class 4.

Class 1

Class 2

Class 3

Class 4

Hard

High Speed

Optical Storage

Magnetic

Drives

Optical Drives

Drives

Storage Drives

 

 

 

 

ATA-100

DVD

R/W CD-ROM

LS-120

ATA-66

DVD-CD R/W

CD-ROM

Tape

ATA-33

 

 

Zip

 

 

 

 

General Attach Guidelines

■The lower the device class number, the faster the device and the more bandwidth required.

■Drives installed in the Device 0 positions on both the primary and secondary controllers receive the greatest possible bandwidth.

■The bootable ATA hard drive should always be installed on the primary controller in the Device 0 position.

4.3.2Attach Sequence Rules by Class Priority

Drives should be attached in the sequence shown for optimum performance starting at position 1.

4 1

32

 

 

Primary

4

 

 

1

 

 

Controller*

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Secondary

3

 

2

 

 

Controller

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Device 1

Device 0

*If there are three or more devices, two or more of which are hard drives, two hard drives should be attached to the primary controller first before following the General Attach Sequence Rule.

 

Service Reference Guide, dx2000 uT

359782-002

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