Component of a Hard Disk Drive

May 25
21:17

2010

Suwanto

Suwanto

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Components used in HDD can be broadly classified into 4 categories – magnetic components,Component of a Hard Disk Drive Articles mechanical components, electro-mechanical components, and electronics. In hard disk drive, information bits are stored in concentric data tracks on a rotating disk coated with magnetic media. The information is recorded as well as retrieved using the read/write head. Practical realization of such non-volatile storage and retrieval of binary bits, however, involves many other essential components, e.g., a motor to spin the disks, an actuator to make read/write head access the desired data etc.

 

Head and Disk

 

Data is recorded on a continuously spinning disk made of aluminum or glass and coated on both sides with a thin layer of magnetic material. The disk is mounted through a hole at the center on the shaft (spindle) of a motor that spins the disks. In desktop application, the disks are spun at 6,000 or 7,200 RPM. The spinning speed can be 10,000 RPM or beyond in high performance HDD. Disk is coated with several layers of other materials.

 

Electromechanical Components

 

Two different electromechanical components are used in a hard disk drive - (1) a spindle motor to spin the disk or disks and (2) an actuator to re-position the read-write heads on the desired data track and to maintain its position precisely over the track while data is being read or written.

 

Mechanical and Electronic Components

 

The drive enclosure is the external casing of the hard disk drive. It provides features for mounting the drive in the drive bay of the host system, and supports other components of the HDD such as spindle motor, actuator, PCB etc. There are two parts of the enclosure - top cover and base plate. All components are assembled on the base plate.

 

Electronic components of an HDD can be categorized according to the following functions:

1. Electronics for reading/writing also known as the channel electronics.

2. Electronics for spinning the disks and positioning of the read/write head also known as the servo channel.

3. Electronics for controlling various operations (such as read data, write data, transfer data between HDD and host etc) of the disk or the disk controller.

4. Electronics for interface with the host system.

5. RAM, ROM etc.