How Hard Disk Works?| Hard Disk Interface

Today, In this post you are going to know about how hard disk works, their interface, how to format the hard drive, and information related to External hard-drive.

The hard disk is the storage device that a computer uses to store information. This is also called a hard drive or fixed hard drive.

Some hard drives located outside the computer and plugged into the back of the computer are called external hard drives.

The computer’s hard drive is the first most important type of storage. Anything that you download, applications that you install, your pictures, videos, and music are all stored directly to internal drive by default.

The system unit on most desktop and notebook computers contains at least one internal hard disk. Current personal computer hard disks have storage capacities from 160 GB to 4 TB and more.

The speed of the hard disk is measured in RPM (Revolutions per minute). While the computer is running, the platters in the hard disk rotate at a high rate of speed. This spinning, which usually is 5,400 to 15,000 revolutions per minute.

 A fast hard drive will have higher RPM. The faster the hard drive spins, the faster your hard drive can read and write data.

Hard disks are read/write storage media. This is, you can read from and write on a hard disk any number of times. If the computer contains only one hard disk, the operating system designates it as drive C.

Additional hard disks are assigned the next available drive letter. Some used a second hard disk to duplicate the contents in case the first is damaged

How Hard Disk Works?

In this heading, you are going to read about how hard disk works. Most hard disks have multiple platters stacked on top of one another. All the platter has two different read/write heads, one for each side. The hard disk has arms that move the read/write heads to the proper location on the platter.

The location of the read/write heads is often referred to by its cylinder. A cylinder is the location of a single track through all platters.

For example, if a hard disk has 6 platters (12 sides), each with 1,000 tracks, then it will have 1,000 cylinders with each cylinder consisting of 12 tracks (2 for each platter).

A single movement of the read/write head arms can read all the platters of data.While your computer is running, the platters in the hard disk rotate at a high rate of speed, usually 5,400 to 7,200 revolutions per minute (RPM).

The platters typically continue spinning until power is removed from the computer. The spinning motion creates a cushion of air between the platter and its read/write head.

This cushion ensures that the read/write head floats above the platter instead of making direct contact with the platter surface. The distance between the read/write head and the platter is approximately two-millionth of an inch.

Dirt, hair, dust, smoke, and other contaminants could cause the hard disk to have a head crash. A head crash occurs when a read/write head touches the surface of a platter, usually resulting in a loss of data or sometimes loss of the entire drive. Now you have understood that how hard disk works in the computer.

How Hard Disk Works

Hard Disk Interface

The hard disk interface is the connection between the hard disk to the PC. The hard disk interface sometimes refers to a hard disk controller. A hard disk controller (HDC) is the interface for a hard disk on a personal computer. The types of available interfaces should be understood.

Serial Advanced Technology Attachment (SATA) is a computer bus primarily designed for the transfer of data between a computer and hard disk drives. The benefits are faster transfers, the ability to remove or add devices while operating, thinner cables that let air cooling work more efficiently. SATA offers performance as high as 3.0 Gbit/sec per device with the current specification.

Enhanced Integrated Drive Electronics (EIDE) is the most widely used controller for hard disks. Four hard disks at 137 GB per disk can be supported by EIDE controllers. Instructions and information to and from the disk at rates of up to 66 MB per second can be transferred through them.

 SCSI (Small Computer System Interface) which also uses parallel signals, can support up to eight or fifteen peripheral devices. Supported devices are hard disks, optical disc drives, tape drives, printers, scanners, network cards, and many more. Some computers have an in-built SCSI interface, while some others use an adapter card to add a SCSI interface. SCSI interfaces provide up to 640 MBps data transfer rates.

 SAS (Serial-Attached SCSI) is the latest type of SCSI that uses serial signals to transfer any type of data, instructions, and information. Advantages of SAS over parallel SCSI include thinner, longer cables, reduced interference, less expensive, support for many more connected devices at once, and faster speeds. SAS interfaces have data transfer rates of 750 MBps and higher.

Format hard drive

Your hard drive must be formatted before you can use the drive to store data. Formatting a hard drive involves three steps.

Low-Level Format

The Low-level format is the first step in formatting a hard drive. The manufacturer of the hard drive performs a Low-level format when the hard drive is produced.

During a Low-level format, the surface of each disk in the hard drive is divided into circles, called tracks. The tracks are then divided into sections, called sectors. The hard drive will store data on the tracks and sectors.

A Low-level format also marks any tracks that cannot store data. The hard drive will not attempt to store data on bad tracks. It is normal for a hard drive to have some bad tracks.

Partition of Hard drive

The second step in formatting a hard drive involves creating partitions. Some operating systems include software you can use to create partitions.

When you create a partition, you assign a drive letter to all or part of a hard drive. You must create at least one partition before you can use a new hard drive.

You can also create additional partitions. Each partition acts as a separate hard drive and can have its own operating system. This allows you to store different types of data in each partition.

High level formatting

The last step is preparing a hard drive to store data in a high-level format. You can perform a high-level format using any operating system. During a high-level format, the operating system created a table of contents for the hard drive.

This prepares the hard drive to store and manage data. If the hard drive has multiple partitions, you will have to perform a high-level format on each partition individually. formatting is part of a hard disk interface.

External Hard drive

External hard drives are exactly the same as internal drives with one exception rather than being enclosed inside the computer the external hard drives are a separate freestanding hard disk.

The External hard drives can be connected to the computer through USB2.0, ESATA, Firewire 400, and Firewire 800. External hard disks have storage capacities of up to 4 TB and more.

How Hard Disk Works


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