Explanation Of Internal Hard Disk Drive Components
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This page provides a look into the various components that construct a hard disk drive.
Explanation Of Internal Hard Disk Components
The illustration shown below is a graphical depiction of an IDE based hard disk drive. Click on a specific component within the image to read more information about how the part operates.
class="TableHeader" > Explanations Of All Hard Disk Drive Components
Hard disk drives are completely sealed to prevent dust and other sources of contamination from interfering with the operation of the hard disk components. The hard drives are not air tight, but rather utilize an extremely fine air filter, to allow for air inside the hard drive enclosure to disipate heat effectively.
spindle motor in the drive is responsible for spinning the platters
and precisely controlled through the unit. They are set to
spin the platters at a fixed rate, usually ranging from 3600 RPM
(Rotations Per Minute) to 7200 RPM. More expesnive hard disk drives spin at 10,000 RPM.
READ / WRITE HEAD
The read/write head is responsible for controlling how data is read from and written to the drive. The gap
between the platters makes room for the magnetic heads to perform its functions. These read/write heads work on the same principles as a floppy disk drive's read/write head but a much faster speed.
A hard disk drive can have at least two or three platters also referred to as heads. Larger hard drives will have a larger quantiy of heads. The actual heads are comprised of an
aluminum alloy material or a mixture of glass and
ceramic material, covered with a special magnetic
The platters are stacked on top of
each other with a common spindle entitled a Head Actuator Arm used to "steer" the platters in the correct orientation so that required data and files can be accessed properly. These platters normally contain a multitude amount of sectors. Each chunk can house a certain amount of data in the form of files and folders. A modern hard drive is designed with approximately 512 bytes per sector.
A hard disk connector is a pathway for data to flow to the motherboard's storage connector. This connector can either use a 40 pin connector (for IDE based hard drives), a 50 or 68 pin connector (for SCSI hard disk drives), or a 4 pin connector (for SATA hard drives).
VOICE COIL ACTUATOR
The voice coil actuator, is an electrical motor which moves or "steers" the head actuator arm.
MOLEX POWER CONNECTOR
The molex power connector on all hard drives provides a power connection to the hard drive. Molex connectors have been around since the evolution of the 8088 computer and will continue to be the primary power type for Ultra ATA hard disk drives and optical storage drives.
MASTER SLAVE JUMPER PINS
These pins on a ATA hard drive are used to control the "chain of command" of IDE devices within the computer. In a system supporting the ATA standard four hard drives can peacefully coexist, using a master and slave configuration. This chain of command simply refers to what device is set up as the master device and what device is set up to use the slave mode. In an Ultra ATA system, two channels coexist labelled respectively IDE0 and IDE1. There can exist two devices on channel IDE0, and two devices on channel IDE1.
40 PIN IDE CONNECTOR
This 40 Pin IDE drive connector allows for the transmission of data between the hard drive and other components in the system. IDE is an older style technology but still remains in popular method for connecting IDE based devices to the motherboard's connections. A large number of workstations still implement IDE technologies since it is cost effective and is compatible with the majority of motherboards old-school and new. IDE devices are also referrred to as PATA (Parellel ATA); both terms reference the same style of hard drive technology.
HEAD ACTUATOR ARM
The head actuator arm turns the entire package of platters several thousand times per minute. The technical term for this is Rotations Per Minute (RPM). Most modern drives can spin the platters at 5400 RPM, while other high end hard drives (such as the ones located in server systems) spin at an incredibly fast 10,000 RPM. Laptop hard drives are typically slower drives spinning at 4200 RPM, although much faster drives are incorporated into newer, more expensive laptop computers. All disk platters in a hard drive are attached to the head actuator arm. This device actually directs the read / write heads as to where to move to access required data called by the Central Processing Unit (CPU). When the CPU calls for a particular sector of data, it locates the head, the track number, as well as the exact sector containing the data. It reads
this data from that particular section and sends it back to the processor for further calculation. The time it takes for the head actuator to park the read/writehead into the correct position over a desired track is called the period. The latency period is a common specification for measuring a hard drive's performance.
Table 1.1 - Explanation Of Hard Hard Disk Drive Components