What is a Hard Disk Drive (HDD)?

Admin
3 Dec, 2023

Hard Disk is installed in everyone's laptop and computer. This is the most important part of the computer. The most valuable thing is people's personal and professional data, which everyone wants to store securely. The main function of a hard disk is to store data in electronic form. 

In such a situation, almost everyone wants to get a good reliable storage device. Its data storage capacity must be so much that all the data related to the needs of the people can be stored. In such a situation, buying a Hard Disk Drive (HDD) at a cheap price is the best option for us. 

HDD started being used commercially in 1957 when IBM company started production of Model 350 Disk Storage. This hard disk was used with the IBM 305 RAMAC system. Thus the IBM RAMAC is generally considered to be the seminal patent for disk drives. 

This is a fun fact that initially, the diameter of disk storage was 24 inches, but with technology and time it has been reduced to today's standard size of 3.5 inches and 2.5 inches. Let us now understand, what is Hard Disk?

HDD

What is an HDD (Hard Disk Drive)? (Definition)

A hard disk or hard disk drive is a hardware device of a computer. It is also called a memory storage device. Its main function: It stores data in electronic form, and is used as a secondary memory storage device.

It is a non-volatile type of storage device. Non-volatile means that the data stored in it remains safe even when the computer is turned off and can be retrieved after the power is turned back on. To communicate with the host, SATA, SAS, PATA etc. communication ports are provided in HDD. A PATA communication port was provided only in older computers, but this port is no longer available. It uses the AHCI protocol.

An HDD consists of a platter, or rotating disk, made of a non-magnetic material, but coated with a thin layer of magnetic material. You also know that all information entered into a computer is in digital form. It is called binary code (01001).

This information comes to the HDD in the form of digital electrical signals, where these signals are recorded in magnetic form in the various fields present on the platter. Note that here only 1 code is entered as +ve, and 0 is omitted.

Parts of the Hard Disk Drive

Parts of the Hard Disk Drive


  • Platter: It is in the shape of a circular disc, which is mostly made of materials like aluminium, ceramic, glass etc. Magnetic coating is done on it. In this, many different circular tracks are made, where many sectors are made inside one track. Data is recorded in this. 
  • Spindle: It is an axis of the platter, which keeps it at a particular place and rotates the platter with the help of a brushless motor. 
  • Head: Two small magnetic transducers are installed on it, which are used to read and write data. 
  • Arm: It works like a lever, which keeps moving back and forth on the platter on receiving power from the actuator so that the magnetic transducer mounted on its head can read/write the data present in any sector. 
  • Arm Axis: It is a Fixed Movable Point, which can easily rotate without leaving its place, meaning it is the center point of the Arm. 
  • Magnetic Actuator: It is made of Copper Coil, which converts electric power into mechanical power. Depending on the electrical power received, it keeps the arm rotating here and there. 
  • IDE Connector: Its full name is Integrated Drive Electronics, which is connected to the IDE port present on the motherboard. 
  • Power Connector: In this, the output power cable for the HDD from the computer's power supply unit i.e. SMPS is connected. 
  • PCB: Its full name is Printed Circuit Board, controller and other chips are present on it. 

How does HDD work? 

  1. If any data is to be entered into the HDD, first the processor converts the input data given by us into binary form. This binary form can be octa, deca or hexadecimal. For example 'A' is a hexadecimal number. , and its binary form is 1010.
  2. Now this data comes through the IDE port in the form of electronic signals or impulses, which are received by the controller present on the HDD.
  3. The controller sends an electric signal to the actuator based on its understanding of this data, causing the actuator to move back and forth.
  4. Here the actuator actually finds the address at which it has to store the data sent to it.
  5. Now as soon as the actuator confirms that the data is to be recorded at address xxxx, the transducer present at the actuator head will give the message that 1010 is to be stored at address xxxx. One thing to know is that computer data is also recorded somewhere, that is, all data has its own specific address.
  6. Then, the transducer and actuator together magnetize the small iron nails present in the sector for 1010 data. Here, for the 1 present in the binary data, the +Ve magnetic field imprint is left.
  7. Now if you want to read 1010 on the computer screen, the magnetic field is scanned again by the read head, and the whole process is repeated in the opposite direction and sent to the processor.

Types of Hard Disk

Different types of hard disks are explained below:

1) PATA HDD: Its full name is Parallel Advanced Technology Attachment. It was used for the motherboard present in old computers. For example Pentium 4, Pentium 5 etc. The PATA HDD is connected to the IDE port on the motherboard via a PATA ribbon cable. Its latest generation data transfer speed ranges from 100 to 133 MB/s. The PATA ribbon cable has 40 pins. 

PATA HDD


2) SATA HDD: Its full name is Serial Advanced Technology Attachment. This is the HDD of Updated Next Generation Technology of PATA HDD. This is the current (circa 2006-2021) appearance used for motherboards. However, now SSD HDD has started being used in new generation laptops.

SATA HDD uses AHCI protocol and it uses SATA LAN. Its interface is also SATA. The full name of AHCI is Advanced Host Controller Interface. The most common size of SATA HDD is 2.5 Inch, which is available in almost all computers and laptops. Its rotation speed ranges up to 4800 RPM, 5400 RPM, 7200 RPM etc. The higher the RPM, the higher the data transfer speed. 

3) SSD: Its full name is Solid State Drive.

This is the latest advance in the world of HDT i.e. Hard Drive Technology. It is made up of non-volatile flash memory. Due to this its data transfer speed is higher than all types of hard disks. Data transfer speed of SATA3 SSD is up to 600MB/s. It uses a DRAM Cache to store data permanently. However, there are many types of SSD As:

  • SATA SSD
  • M.2 SATA SSD
  • mSATA SSD
  • M.2 PCIe SSD
  • M.2 NVMe SSD etc. 
4) SCSI HDD: Its full name is Small Computer System Interface. Its size is smaller than all the hard disks given above. That is why it is especially used in small laptops and compact systems, tablets. But on the basis of its speed, it is mostly used by enterprise companies. 

Its interface type is also SCSI, which has 68pin (HD68). Its Form Factor i.e. physical size is 3.5i x1.0. And its rotation speed can be up to 15,000 RPM. Its storage capacity is not high, but you can get up to 300 GB capacity in the market. It is expensive compared to other hard disks. 

What are the features of HDD?

Although HDD can have many features. It is not possible to tell about everyone. I have told you about the common features below. 
  • Data Transfer Speed: Data transfer speed in HDD is measured by RPM (Revolution Per Minute). RPM means how many times the platter installed in the hard disk rotates in a minute. For example, the rotation speed of an HDD can be up to 4200, 5200, 5400, and 7200 RPM etc. respectively. The higher the RPM, the faster the data transfer speed. Speeds up to 6.0 Gb/s in a typical HDD. 
  • Storage Capacity: This tells the maximum amount of data i.e. file size that can be stored in an HDD. Here storage capacity is measured in GB (Gigabytes) and TB (Terabytes). For example: 512 GB, 1 TB etc. 
  • From Factor: This tells the physical size and weight of the hard disk. For example: 3.5 inches and 2.5 inches width. Generally, 3.5 inches has more storage capacity and is mostly used in servers. And 2.5 inch From Factor hard disk is used in personal computers and laptops. 
  • Hard Disk Interface: It is a device that connects the HDD to the host i.e. other controller or chipset of the computer, so that communication can develop between the two. Serial ATA i.e. SATA interface is used for the latest HDD. 
  • Protocol: It is a set of rules. This means, through which rules any communication i.e. exchange of data will be done. HDDs mostly use the AHCI protocol.  Learn more about the AHCI protocol.
  • Hard Disk Rotational Speed: It is measured in RPM. Such as: 5400 RPM, 7200 RPM etc. 
  • Brand: This shows the trustworthiness of a company, if you buy HDD of a good company, you can get better benefits like a service Warranty. Below you will know the names of the top 5 best companies which are more popular in the field of manufacturing HDD. 
  • Compatible Device: This means which device your HDD is made for use in. For example, laptop, computer and both laptop and computer etc. 

What are the benefits of HDD?

  • Cheap: HDD is much cheaper than other types of hard disks if we compare it on the basis of storage capacity. Overall, this is the best option for a normal computer user. 
  • Permanent Storage: It stores any type of data permanently for a long time. The data recorded in it remains safe when the electric power is turned off. 
  • Portability: We can easily take it from one place to another. 
  • Data Recovery: If due to some reason the data on the hard disk gets deleted, then we can recover the data back. There are many software available in the market for data recovery in the name of data recovery. Like: Disk Drill, Stellar Data Recovery, FonePaw Data Recovery etc.
  • Compatibility: It supports multiple systems. Meaning, there is a greater chance that we can use an HDD with the same form factor in both laptops and computers. And HDD of any brand can be installed in any laptop, and it also works well. 
  • Easy Installation: Installing this type of hard disk is easy for a normal person.

What are the disadvantages of HDD?

  • Noise: Since it is a mechanical storage device, there is noise in HDD, 
  • Data Transfer Speed: Its data transfer speed can be up to 120MB/s, which is less than an SSD Hard Drive. 
  • Power Consumption: HDD consumes more electricity because it uses a brushless motor to rotate the platter. 
  • Size & Weight: Its weight is heavy and size is big.
  • Failure to Shock: This type of hard disk gets damaged when it falls or gets a shock. 

Names of top 5 popular companies manufacturing HDD

  1. Seagate
  2. Western Digital (WD)
  3. Toshiba
  4. Samsung
  5. A-DATA

FAQs

What is the full name of HDD?

The full name of the HDD is Hard Disk Drive.

What is the main function of HDD?

The main function of HDD is to store data permanently in electronic and magnetic form.

What is the difference between HDD and SSD?

A platter is used to store data in the HDD, which keeps rotating. Whereas DRAM Flash Memory is used to store data in SSD.

Which company first created Hard Disk Drive and when?

Hard Disk Drive was discovered by IBM engineers in a San Jose California laboratory. Accordingly, IBM company first created a Hard Disk Drive in 1953.

What does IOPS mean in Hard Disk?

The full name of IOPS is Input/Output Operations per Second. This means how many operations can be completed in one second.

What is AHCI? Tell me its full name?

It is a protocol, which is used for data transfer. Its full name is Advanced Host Controller Interface.

What is Platter? Why is it used in HDD?

It is in the shape of a circular disk, and a magnetic coating is done on it. Many circular tracks are made in it, where many sectors are made inside one track. Data is recorded in this.

Tell me about the types of Hard Disk?

1. PATA HDD 2. SATA HDD 3. SCSI HDD 4. SSD

Learn More...

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