HP d248 HP Compaq Business Desktop d200 Series Personal Computers Service Refe - Page 27

Device Classes, 4.3.2 Attach Sequence Rules by Class Priority, General Attach Guidelines

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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 Hard Drives ATA-100 ATA-66 ATA-33 Class 2 High Speed Optical Drives DVD DVD-CD R/W Class 3 Optical Storage Drives R/W CD-ROM CD-ROM Class 4 Magnetic Storage Drives LS-120 Tape 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. 4.3.2 Attach Sequence Rules by Class Priority Drives should be attached in the sequence shown for optimum performance starting at position 1. 4 1 3 2 Primary Controller* 4 1 Secondary Controller 3 2 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, d200 336493-004 4-3

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Service Reference Guide, d200
336493-004
4–3
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.
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.
4.3.2 Attach Sequence Rules by Class Priority
Drives should be attached in the sequence shown for optimum performance starting at
position
1
.
*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.
Class 1
Hard
Drives
Class 2
High Speed
Optical Drives
Class 3
Optical Storage
Drives
Class 4
Magnetic
Storage Drives
ATA-100
ATA-66
ATA-33
DVD
DVD-CD R/W
R/W CD-ROM
CD-ROM
LS-120
Tape
Zip
1
2
4
3
Primary
Controller*
4
1
Secondary
Controller
3
2
Device 1
Device 0