Serial and Parallel ATA Drive Guidelines and Features

The drive attached to a channel must have a drive designation. If a drive is attached to the Device 0 cable position and its cable-select jumper is present, the drive is designated as Device

0.Similarly, if a drive is attached to the Device 1 cable position and its cable-select jumper is present, the drive is designated as Device 1.

For optimal performance of a computer system, all drives need to be attached to the PATA channel(s) in a specified sequence. This sequence is determined by the device class of the drives and by specific attach sequence rules.

4.3.1 PATA Device Classes

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 channel. 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

 

 

 

 

Only MultiBay

DVD

R/W CD-ROM

Zip

hard drive is

DVD-CD R/W

CD-ROM

 

supported

 

 

 

 

 

 

 

General Attach Guidelines

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

■A drive installed in the Device 0 position receives the greatest possible bandwidth.

4.4ATA SMART Drives

The Self Monitoring Analysis and Recording Technology (SMART) ATA drives for the HP Personal Computers have built-in drive failure prediction that warns the user or network administrator of an impending failure or crash of the hard drive. The SMART drive tracks fault prediction and failure indication parameters such as reallocated sector count, spin retry count, and calibration retry count. If the drive determines that a failure is imminent, it generates a fault alert.

4.5 Drive Capacities

The combination of the file system and the operating system used in the computer determines the maximum usable size of a drive partition. A drive partition is the largest segment of a drive that the operating system can properly access. Therefore, a single hard drive can be subdivided into a number of unique drive partitions in order to make use of all of its space.

Because of the differences in the way that drive sizes are calculated, the size reported by the operating system may differ from that marked on the hard drive or listed in the computer specification. Drive size calculations by drive manufacturers are bytes to the base 10 while calculations by Microsoft are bytes to the base 2.

 

Service Reference Guide, dx5150

361685-001

4–5