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Internal Storage Area in Hardware

August 6, 2009
tags:
Hard disk drive
A hard disk is part of a unit, often called a “disk drive,” “hard drive,” or “hard disk drive“.
It is used to store and provide relatively quick access to large amounts of data on an electromagnetically charged surface or set of surfaces. Hard disk contains several billion bytes (gigabytes) of storage.
Hard disk is a permanent data storage device built into all desktop PCs that permits you to save and retrieve information, and that stores the computer’s operating system and other software. The size of a hard drive is usually expressed in gigabytes.
Component Description
A hard disk is really a set of stacked “disks,” like phonograph records, which has data recorded electromagnetically in concentric circles or “tracks” on the disk.
A “head” (something like a phonograph arm but in a relatively fixed position) records (writes) or reads the information on the tracks. Two heads, one on each side of a disk, read or write the data as the disk spins.
Each read or write operation requires that data be located, which is an operation called a “seek.” (Data already in a disk cache, however, will be located more quickly.)
A hard disk/drive unit comes with a set rotation speed varying from 4500 to 7200 rpm. Disk access time is measured in milliseconds.
Although the physical location can be identified with cylinder, track, and sector locations, these are actually mapped to a logical block address (LBA) that works with the larger address range on today’s hard disks.
What is a hard disk partitioning?
A hard disk partition is a defined storage space on a hard drive.
Most operating systems allow users to divide a hard disk into multiple partitions, in effect making one physical hard disk into several smaller logical hard disks.
Reasons to Use Hard Disk Partitions
A user may decide to split a hard disk into multiple partitions in order to organize his data more effectively.
On Microsoft Windows machines, it is common to store the OS and applications on one hard disk partition and user data on another hard disk partition.
When a problem occurs with Microsoft Windows, the OS partition can be completely formatted and reinstalled without affecting the data partition.
A user may decide to split a hard disk into multiple partitions because smaller partitions often have smaller cluster sizes.
A cluster size is the smallest chunk of data which a partition can store. A large partition might have a cluster size of 16KB. This means that a file with one character in it will occupy 16KB of space on the disk. In a smaller partition, that file might only require 4KB to store. This is a useful strategy if you are storing a large number of small files.
A user may have to split a large hard disk into multiple partitions if the hard disk is larger than the partition size supported by the operating system.
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