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Install hard drives

Configure CMOS and install drivers

Troubleshoot hard drive installation

Of all the hardware on a PC, none gets more attention—or gives more anguish—than the hard drive. There’s a good reason for this: if the hard drive breaks, you lose data. As you probably know, when the data goes, you have to redo work or restore from backup—or worse. It’s good to worry about the data, because the data runs the office, maintains the payrolls, and stores the e-mail. This level of concern is so strong that even the most neophyte PC users are exposed to terms such as IDE, PATA, SATA, and controller—even if they don’t put the terms into practice.

This chapter focuses on how hard drives work, beginning with the internal layout and organization of hard drives. You’ll look at the different types of hard drives used today (PATA, SATA, SSD, and SCSI), how they interface with the PC, and how to install them properly into a system. The chapter covers how more than one drive may work with other drives to provide data safety and improve speed through a feature called RAID. Let’s get started.

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NOTE Chapter 12, “Implementing Hard Drives,” continues the hard drive discussion by adding in the operating systems, showing you how to prepare drives to receive data, and teaching you how to maintain and upgrade drives in all versions of Windows.

Historical/Conceptual

How Hard Drives Work

Hard drives sport one of two technologies today. The most common type has moving parts; the newer and more expensive technology has none. Let’s look at both.

Platter-based Hard Drives

A traditional hard disk drive (HDD) is composed of individual disks, or platters, with read/write heads on actuator arms controlled by a servo motor—all contained in a sealed case that prevents contamination by outside air (see Figure 11-1).

Figure 11-1 Inside the hard drive

The aluminum platters are coated with a magnetic medium. Two tiny read/write heads service each platter, one to read the top and the other to read the bottom of the platter (see Figure 11-2).

The coating on the platters is phenomenally smooth. It has to be, as the read/write heads actually float on a cushion of air above the platters, which spin at speeds between 3500 and 10,000 rpm. The distance (flying height) between the heads and the disk surface is less than the thickness of a fingerprint. The closer the read/write heads are to the platter, the more densely the data packs onto the drive. These infinitesimal tolerances demand that the platters never be exposed to outside air. Even a tiny dust particle on a platter would act like a mountain in the way of the read/write heads and would cause catastrophic damage to the drive. To keep the air clean inside the drive, all hard drives use a tiny, heavily filtered aperture to keep the air pressure equalized between the interior and the exterior of the drive.

Figure 11-2 Read/write heads on actuator arms

Data Encoding

Although the hard drive stores data in binary form, visualizing a magnetized spot representing a one and a non-magnetized spot representing a zero grossly oversimplifies the process. Hard drives store data in tiny magnetic fields—think of them as tiny magnets that can be placed in either direction on the platter. Each tiny magnetic field, called a flux, can switch north/south polarity back and forth through a process called flux reversal. When a read/write head goes over an area where a flux reversal has occurred, the head reads a small electrical current.

Today’s hard drives use a complex and efficient method to interpret flux reversals. Instead of reading individual flux reversals, a modern hard drive reads groups of them called runs. Starting around 1991, hard drives began using a data encoding system known as run length limited (RLL). With RLL, any combination of ones and zeroes can be stored in a preset combination of about 15 different runs. The hard drive looks for these runs and reads them as a group, resulting in much faster and much more densely-packed data.

Current drives use an