HP Business Desktop dx5150 Series Service Reference Guide, 1st Edition

Service Reference Guide, dx5150 361685-001 4–5
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.
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.
4.4 ATA 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.
Class 1
Hard
Drives
Class 2
High Speed
Optical Drives
Class 3
Optical Storage
Drives
Class 4
Magnetic
Storage Drives
Only MultiBay
hard drive is
supported
DVD
DVD-CD R/W
R/W CD-ROM
CD-ROM
Zip