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What is the full form of HDD

HDD: Hard Disk Drive

HDD stands for Hard Disk Drive. Hard disc, hard drive, and fixed disc are other names for HDD. A hard disc drive (HDD) is a type of data storage device that uses magnetic media to store digital information and rotational platters to retrieve it. Hard drives are the primary storage component of a computer system. Non-volatile memory is present in an electromechanical device. HDDs are used in computers, mobile devices, and consumer technology. They can store operating systems and vast systems of data as well.

Hard disc drives, in particular, regulate the read and write operations of the hard disc on which the files are stored. In a computer, HDDs are either implemented as the primary storage device or as a backup storage device.

They are frequently located in the drive bay and linked to the motherboard using cables in various formats, including Advanced Technology Attachment (ATA), Serial ATA, Parallel ATA, and Small Computer System Interface (SCSI). A power supply device is also linked to the HDD, allowing it to continue to save data even when the power is turned off.

Although a hard drive and a hard disc are distinct objects that are packed together as a unit, either terminology can be used to refer to the entire unit.


IBM engineers developed the HDD in 1953 to offer cheaper, random access to vast amounts of information. The hard disk's initial size equaled that of a refrigerator, and it could contain 3.75 megabytes of data. However, with technological development, hard disc sizes are getting smaller, and by the middle of the 1980s, they were just 3.5 inches in size. Hitachi introduced 1 TB hard drives in 2007, while HGST introduced 10 TB storage devices in 2015. Seagate introduced hard drives made with SMR (Shingle Magnetic Recording) technology. Moreover, HGST created the first hard drive loaded with helium. Helium is employed because it is less thick, colder, and has less weight than air, which improves hard disc performance and drive density.

Importance of Hard Disk Drives

Hard discs are needed as storage devices since they may be used to store OSs, applications, extra storage, and files. Users of computers wouldn't be able to save programs, files, or files to the computers without using hardware like hard discs that can keep track of data even after they are switched off. All systems require at least a single hard drive to store information permanently.

Working on Hard Disk Drives

Most fundamental hard drives are comprised of several disc platters, which are concentric discs composed of aluminum, glass, or ceramic and organized together around a spindle inside a fully sealed environment. A motor attached to the spindle rotates the platter. The data transfer units that use a magnetic head to record information magnetically to and from the loops upon the platters are also included in the chamber. Additionally, the discs feature a narrow magnetic cover.

The motor makes up to 15,000 spins per minute as it rotates the platters. A second motor regulates the location of the data transfer units, which magnetically store and read data on every platter while the platters spin.

External HDDs

The majority of internal HDDs in computers function as described above. Individuals can also buy external hard discs, though. External drives can be used as a portable backup to restore the device or increase a computer's storage capacity. Connectors like USB 2.0, USB-C, or External SATA may attach external discs to a system or other device. Additionally, external drives may deliver data more slowly compared to internal HDDs.

In addition to increasing a device's storage capacity, an external hard disc also has the benefit of being accessible. Users can physically carry their stored data on many devices and access it from anywhere.

HDD Evolution and Technology Developments

Seagate Technology introduced hard disc drives that employ SMR technology in 2013. By stacking the magnetic loops across each disc instead of aligning them parallel to one another, SMR enhances the storage of HDD devices. The tracks overlap so much like shingles on a roof. In 2012, HGST developed the first HDD containing helium. In contrast to traditional HDDs, helium is less dense, cooler, and lighter than air. It also requires less energy, increases drive density and performs better. In 2016, Seagate unveiled a 10 TB helium disc drive 2016.

The Ultrastar DC HC560 and WD Gold HDD Enterprise-ClassClass SATA HDD, two 20 TB HDDs from HDD company Western Digital, were introduced in 2021. The maximum disc drive size currently provided is 20 TB. Both storage devices have a 3.5-inch size but are used for different purposes. The Ultrastar DC HC560 is designed for internet file systems, commercial systems, security, and online backup services. The WD Gold HDD is developed for large businesses with large business applications.

Characteristics of HDD

  • Storage Capacity and Price: As technology advances, HDD prices have dropped while storage capacity has increased.
  • Performance: The HDDs' performance is determined by how HDDs store and retrieve data.
  • Reliability: This refers to the user's freedom to save and retrieve data as needed without encountering any difficulties.
  • Rotations Per Minute: This stands for the hard disk's rotations per minute. The hard drive performs better with higher RPM.
  • To reduce data transfer time, hard drives use disc caching. The greater the cache, the quicker the hard disc.
  • Platters: The number of platters on a hard drive determines its storage capacity.
  • Seek time, also known as positioning performance, is the amount of time required for data reading and writing to reach their intended positions on the disc. It is frequently used with rotational speed to evaluate hard drive performance. Milliseconds are used to measure it.
  • Latency: The amount of time it takes the spinning platter to transport data to the read and write units.

Hard Disk Controllers

Chips and electrical circuits make up the system. Additionally, it regulates the transmission of information, commands, and data from one system to another.

For desktop computers, there are four different types of hard disc connectors, as described in the following:


Serially Advanced Technology Attachment is what SATA stands for. It transports data, commands, and messages via continuous transmissions. The key benefit of SATA is the narrower, longer, and stronger cables. The SATA link, which is substantially quicker than USB, may be used with external disks.


Enhanced Integrated Drive Electronics is what EIDE stands for. The EIDE device interface uses parallel transmissions to transport information such as commands and information. EIDE can transport data at a rate of approximately 133 Mbps.


Small Computer System Interface is the abbreviation for this. It is utilized as a parallel transmitter and is incompatible with devices between 8 and 15. Hard drives, hard disks, scanners, etc., are all supported by SCSI.

4. Disk cache

The performance of an HDD is increased by using it. The user is dealing with a specific form of RAM application and data. When the CPU requires the data, it first checks the cache on the hard drive, and after using the information, it pulls the data from the hard drive.

Advantages of Hard Disk Drive [HDD]

1. Storage Capacity

The hard disc drive (HDD) in current computers has a tremendous storage capacity and can hold a wide range of data. This is the main benefit of HDDs since they can manage such massive amounts of data practically forever.

In 2021, desktop hard disc storage ranged between 1 to 8 terabytes, while the most extensive drives discovered had a potential of 24 terabytes.

2. Non-Volatile

Since the hard disc drive [HDD] is non-volatile, it doesn't often lead to data loss while the power is out. As a volatile memory, RAM [Random Access Memory] cannot retain or save data while the power is off.

We deploy the OS onto the HDD because of its inherent ability to store data, which contributes to the device's ability to operate. Not just the OS but also all the essential programs and applications that are crucial to our system. The use of HDD is increasing due to this function, which is helpful for individuals who need to store large amounts of data on the hard drive, such as photographs, documents, movies, and so on.

3. Cost

It should go without saying that the size and storage of an HDD significantly impact its pricing. You must select the hard disc based on your needs from various sizes. In comparison to SSD, the price of HDD is lower. Traditional hard discs (HDDs) perform substantially better than SSDs. Due to the SSD's larger number of revolutions per second than the HDD, its speed is considerably faster.

Therefore, you should make your decision based on your requirements. An SSD is the way to go if you want a performance-based disk. If speed is not a concern for you, a standard HDD is the way to go.

4. Easy Availability

The need for computer products expanded significantly due to the intense demand in the IT industry, particularly in the computer accessories segment. As a result, manufacturers worldwide have significantly boosted their output.

Because these companies released their products, which they had produced in massive quantities, getting a computer hard drive or SSD in the marketplace is simple.

The larger hard disc producers, including Samsung, Toshiba, Seagate, and others, have also hired regional sales executives in every metropolis worldwide. Additionally, their main responsibility is to investigate the production and accessibility of computer products.

5. Can't Misplace It Easily

The computer's internal hard drive is mounted within the container, also known as the computer cabinet, with screws securely fixed to its four ends.

Unlike an external hard drive, which is linked to a computer system through a USB connector attached to the front or back of the cabinet or case, it is very tough to misplace your hard drive.

6. Faster than Optical Disks like DVDs and CDs

Compared to DVDs and CDs, HDDs have a higher data transfer speed and a greater potential for data storage.

7. Easily Replaceable and Upgradeable

With the use of screws, the hard drives are attached to the computer cabinet. You can restore your destroyed or corrupted hard disc with a brand-new one that you buy from the store. Regardless of the size, volume, or brand, HDDs are widely accessible in the marketplace.

Before updating the HDD to the latest version, one should create a backup of all of their vital data and records. It must be done regularly to prevent damaged data and any data loss.

8. Cheap to Manufacture

Hard disc drives are more affordable than you might expect since the raw materials used to make them are so less costly. Buying raw materials in large quantities further brings down costs.

9. Small in Size & Portable

Due to their compact size, HDDs are easy to move from one place to another.

They fit easily within the computer cabinet because of their exceptionally small size and design.

An external HDD may be transported from one place to another in our backpacks or in our hands. This HDD also has a lot of data that can be readily duplicated to other media.

Disadvantages of HDDs

1. Speed

The amount of time before data is transferred is the spinning drive's reaction time. The spinning drive's circulating discs and moving units have mechanical properties that largely govern this duration. The hard disk's speed is mainly dependent on its revolutions per minute. The RPM range for inexpensive HDDs is 5200 to 7200, but the range for expensive HDDs is 7200 to 10,000.

In simple words, it may be noted that HDDs with greater RPMs than others often operate more quickly.

2. Noise

The moving units and noisy platters of the earlier HDD, including a moving component, are both components.

Each of the two sides of this HDD, which includes many discs and is referred to as a platter, is made to store and manage data. And these platters are used for reading and writing. They are placed on top of one another and rotate in accordance with their arrangement. When operating on a large program, such as installing windows, transferring large files, multitasking while playing a game, or downloading content from the internet, these read-write activities create noise.

3. Gets Damaged Easily

The HDD is made up of moving components, and the moving platters are used to store the information and files. The heads of an HDD have one head per platter and are all attached to a single arm. The head travels quickly and violently over the disc and is placed on a rack that is known as an actuator. Due to the hard device's rapid speed, the loss is readily possible. HDD speed is measured in RPM (revolutions per minute). Many contemporary discs rotate the platters at speeds of around 4200, 7200, and 15000 revolutions per minute (rpm).

4. Power Consumptions

An HDD is made up of a circulating disc with moving units that store information in pathways and sections on the disc.

Since the continuous rotating of platters requires more energy, hard discs are believed to consume more energy than traditional HDDs.

5. Fragility

The HDDs are extremely brittle and are readily broken when handled violently.

When they are connected to the computer case, they are less prone to attack. Their heads are readily destroyed by bumps or buzzing.

Even when functional storage devices are dropped from a height, they usually stop performing very quickly, necessitating replacement in most instances.

6. Dependencies

The rotating components, known as heads and platters, are the only components used by HDD. These pieces regularly travel within their designated positions, and the entire HDD becomes useless if they abruptly stop operating. Occasionally, this overreliance might result in a loss of data.

7. Regular Backup

The files and records on the hard disc drive must be continuously backed up to other systems. Since the hard disc has several moving components and is vulnerable to damage, it is advisable to make a backup of your crucial data frequently. Data recovery is a costly alternative, and, indeed, it is tough to retrieve misplaced or deleted items. Therefore, taking measures is the best decision to resolve this condition.

8. Irregular Startup and Shut Down

When the heads are switched off in most drives, they fall on the platters as they stop moving.

Each head is sustained for a short time while the drive operates due to a highly narrow air cushion. Inadequate operating system disruptions or uneven electrical energy might harm the HDD by causing negative sectors that are exceedingly challenging to fix.

Hard Drive Components and Form Factors

The spinner, disc platter, operator, controller arm, and recitation head are all parts of a hard drive. The set of mounted discs, or the portion of the HDD that stores and allows access to data on an electromagnetically charged area, is termed the "hard disc drive." However, the term can also apply to the entire device.

The physical dimensions or shape of the device that stores data are referred to as the hard disc drive form factor. The size, location, and alignment of the host interface connection, as well as the size, width, and altitude of HDD form factors, are all controlled by a number of industry norms. Common functionality with various computing devices may be established by using an industry-standard compact design.

Enterprise resource planning systems most frequently use hard disc drives in the 2.5-inch and 3.5-inch dimensions, commonly known as small form factor and large form factor, respectively. The 2.5-inch and 3.5-inch dimensions roughly indicate the platter's diameter within the drive shells.

Despite the existence of additional form factors, manufacturers stopped working on devices with 1.3-inch, 1-inch, and 0.85-inch devices by 2009. These alternative form factors became all but useless due to flash's declining cost. It's also vital to remember that although exact measurements are listed in millimeters, statutory sizes are given in inches.

Additionally, many SSDs are made with the HDD form factor in consideration.

Solid state drives that share the same ports as hard disc drives often transport information to and from the host computer via the SATA or serial-attached SCSI (SAS) connection.

Common Hard Disk Errors

There are many different causes of HDD failure. Failures, however, typically fit into one of the following six major types.

  • A power surge, for example, can destroy the hardware in a hard drive, causing the read-or-write unit or computer system to fail. When an HDD turns on but cannot retrieve, store or load data, a number of its components probably have an electrical fault.
  • Mechanical failure and a hard incident, such as a hard drop, can result in mechanical malfunction. This might result in the read/write disc head smashing against a spinning platter and doing permanent physical harm.
  • A logical fault occurs when the programme on the hard drive is corrupted or stops working normally. A logical failure can result from several types of data deterioration. This includes mistakenly removing files that are essential to the operation of the HDD or damaged files, malware, viruses, wrongly terminating a programme, or closing a computer down.
  • When the magnetic media on a hard disk's rotating platter is out of alignment, a bad sector fault can happen, rendering a particular region of the platter inaccessible. When they do occur, bad sectors are frequently contained. However, a computer crash, unavailable data, or the hanging or delaying of a computer's functions may result from a rise in the number of faulty sectors over time.
  • A firmware error occurs when the programme that saves the disc and allows the HDD to connect to a computer is damaged or stops working properly. An HDD attached to a computer may not recognize or incorrectly identify itself as an HDD due to this kind of loss, or the disc may seize during system startup.
  • Multiple unidentified errors may accumulate over time. For example, an electrical issue could trigger a mechanical problem, like a read/write unit failure. It could also cause a rational failure, causing the hard disc drive platters to generate several faulty areas.

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