Friday, June 24, 2011

Hard Disk Drive (HDD)

Hard disk drive or HDD is the basic component of any computer. Hard disk is in fact the data bank where all the information, programs and files are stored. Hard disk contains a round rotating metal disk called platter which is like a mirror in appearance and stores the data with magnetic recording medium. This magnetic recording medium stores the data via read/write head on the platters. These platters are quite delicate and should not be tampered with because even small damage can result in complete loss of data.

Unlike RAM (Random Access Memory) hard disk is classified as non-volatile storage memory as it does not requite continuous power supply to store the data.

Components and Working of the Hard Disk Drive

Read and write heads are attached to the end of the platter and as mentioned are responsible for reading and writing the data on the hard disk.

These read and write heads are attached to the arm called actuator which moves over the platter of the hard-disk. The read and write head never actually touches the platter but just brushes past it with constant air cushion between both of them.

Platter rotates with the speed of over 5000 RPM in the hard disk. A component called spindle is actually responsible for rotating the hard-disk with such speed. The higher the RPM (rotations per minute) faster the data can be read/written on the hard-disk and thus it gives a much better performance.

Hard disk drives available in market come with varying storage capabilities ranging from few megabytes to hundreds of gigabytes. Previously computers used to have a hard drive with just few MB but nowadays most of the computers have over 50 GB of hard-disk space.

All the components mentioned like actuator, spindle platter etc. are contained in the unit called hard disk assembly (HDA). Logic board which controls the movements of these components is located outside HDA and facilitates the inward/outward movement of data.
Internal architecture of  a Hard Disk Drive

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