Everything You Need To Know About Hard Disk Drives

Key Points

  • Different types of hard drives have different functions.

  • Hard drive disks have many moving parts.

  • Solid-state drives are another option instead of hard drives.

  • Weigh the pros and cons when choosing between a hard drive disk and a solid-state drive.

A hard drive disk (HDD) is critical for the use of any computer or electronic device that stores data. Many take this simple yet complex and crucial piece of equipment for granted. It provides a means of storing and accessing files, software programs, and other data on a long-term basis. It’s one of the most common storage devices used in computers and other electronic devices next to solid-state drives (SSD).

Think of a hard drive disk as a filing cabinet. Both organize files, folders, photographs, and important documents in the same way. Also like filing cabinets, HDDs come in a variety of sizes, holding different amounts of documents. Knowing the kind of hard drive to install in your computer makes all the difference in the world.

Different Types of Hard Drives

There are many different types of hard drives on the market, each with its own advantages and disadvantages. This includes internal and external hard drives. More than just computers use hard HDDs. Gaming consoles, surveillance systems, digital video recorders, and various pieces of medical equipment all use HDDs.

Internal Hard Drives

The internal HDD is the most common type as every computer comes installed with one. Hard drives store and boot a computer's operating system along with other primary programs. There are three different types of Internal hard drives.

3.5" and 2.5"

Firstly, there’s the 3.5" HDD. It’s the largest kind of HDD used in desktop computers. Available in both SATA and SAS interfaces, these offer the highest storage capacity. Smaller than the desktop HDD is the 2.5" hard drive, designed specifically for laptops. It’s identical to its larger counterpart but holds less data.

Solid-State Hybrid

The third type of internal HDD is the solid-state hybrid drive. This combines the best of both worlds, using a traditional hard drive and solid-state storage in the same device. The solid-state portions store frequently accessed data, significantly improving the drive’s performance compared to a traditional HDD.

External hard drive connected to laptop

External Hard Drives

Allowing for more portability and additional storage space is the external hard drive. It’s as simple as unplugging from one computer and into another, a convenient option when you need to transfer data between multiple devices. They also come in a variety of sizes, ranging from small, pocket-sized drives that hold a few hundred gigabytes to large desktop drives that hold multiple terabytes of data. These connect via USB or Thunderbolt interfaces, with Thunderbolt offering a faster rate of data transfer.

External hard drives are excellent devices for backing up important data by providing an extra layer of protection in case of hardware failure. They also don’t require any special software to set up and are compatible with both Windows and Mac operating systems.

Network Attached Storage Device

Less commonly used by consumers is the Network Attached Storage device, referred to as a NAS. This is a collection of hard drives in a self-contained unit, consisting of one or more HDDs connected to the network via ethernet. Alternatively, a NAS connects directly to your computer. Connecting it in this manner requires a USB interface.

NAS devices create a shared storage platform for multiple computers on a network optimized for sharing files. Azure and iCloud are a form of NAS, making your own the equivalent of having your personal Cloud storage at home.

Easy to set up and use, NAS devices don't require special or technical expertise to manage. They come in a wide range of sizes, from small, single-drive devices to large, multi-drive devices that store terabytes of data.

One of its key benefits is its ability to support multiple users on the same network to access files from a central location. This makes it an ideal solution for small businesses, workgroups, or households with multiple computers. NAS devices support a variety of file types from documents to videos. 

Another benefit of a NAS device is that it’s configurable with various data protection features, such as Redundant Array of Independent Disks (RAID) or backup software. This prevents loss of data due to disk failure or other problems.

HDD Functions

HHDs are an essential component for computers, providing a reliable means of storing and accessing digital data.

Storing data is a hard drive's main function, but it serves others. In addition to data storage, hard drives also boot up the operating system, accessing the hard drive before any other component of a computer. Without the hard drive, your computer wouldn’t be able to boot up.

While it falls into storing data, hard drives also cache frequently accessed information. This assists with decreasing the time it takes for a program or other data to boot up.

Old hard drives stacks on one another

Hard Drive Parts

An HDD consists of several moving parts, differentiating it from an SSD. The primary part of a traditional hard drive is a thin magnetic disk that stores the data called the platter. HHDs have several platters stacked on top of each other that spin at a pre-set speed that correlates to the rate at which the HDD reads or writes.

Reading and writing the data on the platter are the heads These small electromechanical devices move over the spinning platters and use binary language to write data. An actuator arm connects to the heads and moves them across the platters to access the written data.

Without a motor, traditional hard drives wouldn't work. The motor spins the platters at high speeds (thousands of revolutions per minute), allowing the read/write heads quick access to the data. Like anything else with a motor, they’re prone to wear and tear.

Finally, there's the Printed Circuit Board. The circuit board controls the operation of the HHD, including the movement of the read/write heads, the speed of the spindle motor, and the transfer of data to and from the computer. This is like the nervous system of the hard drive, sending messages to the correlating parts of its body.

When an HDD writes data, it’s divided into small magnetic areas on the platters called sectors. Each sector identifies a unique address that locates the sector on the disk it's written on. The read/write heads move across the platters to the appropriate sector and use a magnetic field to read the data.

HDD Advantages and Disadvantages

With all the different forms of HDDs on the market, it’s important to weigh their pros and cons. Some users opt to forego having a hard drive in their devices altogether, but an HDD might be right for another person. There are several advantages and disadvantages to using a hard drive. 


HHDs store massive amounts of data, reaching up to terabytes. Compared to other storage devices, HDDs manage to stay inexpensive while remaining cost-effective, offering a large amount of storage for a lower cost per gigabyte.

Traditional hard drives are also easy to replace by simply unplugging them from their input port and plugging in a new one. Whether it’s plugged into a SATA, PCIe, or USB port, there’s no difficulty even for the technologically illiterate. 


Unfortunately, HDDs have slower access times. It takes longer for an HDD to read and write data than its SSD counterpart. This is why many users opt to store their operating system on an SSD over an HDD. HHDs are vulnerable to damage from physical shock or vibration due to the many moving parts, causing data loss.

HHDs have a limited lifespan compared to other storage devices. A few years pass before they start to fail, but the moving parts begin to degrade. It’s important to back up your data regularly and replace the hard drive when it shows signs of degradation. It’s time to replace your hard drive when it’s not maintaining the same speed it once was and begins making unusual noises. 

Hard Drive Prices

Several factors affect the price of a HHD. The storage capacity of the HDD is the primary factor with larger capacity drives being higher in price. Other factors that affect the price include the form factor, performance specifications, interface, brand, and model of the drive. Market demand also plays a role in pricing, with higher demand often leading to higher prices.

Storage Capacity

Storage capacity influences price because it requires more components, such as more platters or heads, to store more data. In addition to the physical components, larger capacity HDDs have higher performance specifications. This includes faster rotational speeds, larger cache sizes, and other features that improve their overall performance. It's worth noting that the cost per gigabyte of storage decreases as the capacity of the HDD increases. This means that a larger capacity HDD offers more bang for your buck than a smaller capacity drive.


The size of the drive also influences its price. As stated above, HHDs come in a 3.5" or 2.5" form factor with the smaller version being more expensive.

Internal hard disk drive

Supply and Demand

Supply and demand also play a role in pricing. If there’s high demand for a particular capacity or type of drive, prices go up. Meanwhile, lower demand makes for lower prices. Not often thought about is the supply line. Just as with any other product out there, the lack of transporting goods due to natural disasters or regional disputes influences the cost of products.


SSDs use NAND-based flash memory to store data. Unlike traditional HDDs that contain multiple moving parts, SSDs rely on electronic circuits to read and write data.  It's become the favored storage device in computers due to its high performance and reliability. Furthermore, SSDs lack physical moving components.

SSDs are available in a variety of forms and sizes, including 2.5", M.2, and U.2. From SATA to PCIe, SSDs use as many interfaces as HDDs to provide fast and reliable storage.

Parts of an SSD

While there aren’t any moving parts inside an SSD, they still consist of multiple parts. There are also fewer components within an SSD than in a traditional hard drive.

Memory Chips are the primary piece that make SSDs work. Rather than utilizing a spinning platter, these flash memory chips store the data. An SSD holds several memory chips organized into blocks.

The controller functions much like a combination of the circuit board and heads found in a mechanical hard drive. The microcontroller manages the operation of the SSD, including the reading and writing of data to the memory chips, error correction, and data transfer to and from the computer. It sends the information where it's supposed to go.

Finally, each SSD comes equipped with a cache, a small amount of high-speed memory used to store frequently accessed data temporarily.

An SSD divides data into small blocks and stores it in flash memory chips when it's written. The controller manages the reading and writing of data to and from the memory chips, and performs error correction to ensure data integrity. When an SSD reads its data, the controller retrieves it from the appropriate memory blocks and transfers it to the computer.

SSD Advantages and Disadvantages

Just as every piece of equipment, electronic or otherwise, there are benefits and drawbacks. An updated version of a pre-existing tool might be shinier with more features, but there's something about it that doesn't measure up to its predecessor.

Internal hard drive pieces


One of the biggest advantages SSDs have over other storage devices is that they are significantly faster, offering faster boot times, faster application load times, and faster file transfers. This leads to overall better system performance. SSDs are also more durable since they have no moving parts that break or wear out over time. This also means they’re more resistant to physical shock or vibration damage.

Furthermore, SSDs consume less power, resulting in longer battery life for your laptop or desktop.


One potential drawback of SSDs is that they are typically more expensive than traditional hard drives, and offer less storage capacity per dollar. However, the price of SSDs has decreased over time, and they are now becoming more affordable and accessible to a wider range of users. While manufacturers have improved SSD capacity over the years, they have a limited capacity compared to HDDs.

Then there's the lifespan. An SSD's lifespan depends on numerous factors. The amount of data written to the drive, the type of flash memory used in the drive, and the quality of its firmware all play a role in its degradation.

Although SSDs have some disadvantages, they remain one of the most popular storage devices due to their high performance, reliability, and low power consumption.


Why would anyone want an HDD when SSDs exist? The choice between an SSD and an HDD depends on individual needs. You might live in a digital world, but sometimes analog is better. It's all a matter of preference, though. The budget also plays a role.


Firstly, consider speed. SSDs are faster than HDDs in terms of read/write speeds, significantly improving overall system performance. However, SSDs are more expensive, with a higher cost per gigabyte because of the parts used in manufacturing them. If you need a lot of storage, an HDD is more cost-effective.


Since SSDs don't have the same mechanical pieces as HDDs, they're more durable. HDDs are vulnerable to mechanical failure, resulting in loss of data while SSDs are not as susceptible to this type of failure.

Internal hard drive parts

Storage Capacity

Furthermore, HDDs offer more storage capacity than SSDs, particularly at lower price points. As of 2021, the largest consumer-grade SSDs have a capacity of four to eight terabytes while HDDs have a capacity of up to 16 terabytes.


Lastly, SSDs make no noise while HDDs are noisy due to the spinning platter. However, that noise also lets you know when it's time to replace the HDD, so maybe it's a plus.

Many users choose to use both types of drives, using the SSD used as the drive for the operating system and applications while the HDD manages the mass storage of documents. Or, split the difference by installing a solid-state hybrid drive.

Different Interfaces

All this talk about interfaces leaves a person confused and makes it all seem complicated. However, computers are simpler devices than most think. The most common interfaces you find inside a computer are different variations of USB (2.0 and 3.0), PCIe, SATA, and SAS.


Universal Serial Bus (USB) is the most common interface across all devices. This is the input used for wireless devices or external hard drives. Each version of USB offers different speeds and capabilities, with newer versions offering faster transfer speeds. It's important to ensure that you connect compatible devices with the USB version of the port, as connecting a USB 3.0 device to a USB 2.0 port, for example, results in slower transfer speeds.

Internal hard drive being repaired


Peripheral Component Interconnect Express, or PCIe, is a type of high-speed computer expansion bus that's used to connect peripheral devices. Connect the graphics card, network cards, and storage devices to a computer's motherboard here.

PCIe uses a point-to-point topology, meaning each device connects directly to the CPU via its own dedicated lane. This allows for higher bandwidth and lower latency compared to the shared bus architecture used in older standards. PCIe also supports hot-swapping, meaning devices don't need a reboot when adding or removing a component from a running system.


Then there's Serial ATA, referred to as SATA, a computer interface used to connect HHDs, SSDs, and optical drives to a computer's motherboard. SATA uses a serial bus architecture, meaning data transmits one bit at a time over a single wire rather than in parallel as with the older interfaces. This allows for faster data transfer rates, as well as simpler and more compact cables. SATA cables have seven pins and come in different lengths.


Finally, similar to SATA is the Serial Attached SCSI (SAS). This interface also connects high-performance storage devices to a computer's motherboard. SAS interfaces create more demanding enterprise applications requiring faster rates for data transfer. SAS interfaces support multiple devices on a single cable with each device having its own address. This allows for more flexibility in storage configurations.

Trusted Brands

There are a number of companies that have been in the business of manufacturing and selling HDDs for a long time. Some focus solely on computer peripherals while others also manufacture actual computers.


Toshiba is a well-known and respected electronics manufacturer with a wide range of products across multiple industries. It's one of the world's leading laptop manufacturers, producing a range of models for different markets and user types, from budget to high-end professional laptops.

Toshiba is one of the largest producers of hard drives, producing both traditional hard drives as well as SSDs.


Seagate is another top brand in the market that designs, manufactures, and sells a range of data storage products. It's known amongst tech enthusiasts as one of the largest HDD producers in the world, producing both internal and external drives for desktops, laptops, and enterprise-level storage. It has a reputation for its reliability and high-quality products. Its electronic catalog is vast, selling electronics from storage devices to security devices.

Their NAS devices provide centralized storage for small businesses and home networks.

Take the Wheel When It Comes to Computer Drives

The bottom line is that hard drives are a crucial part of a computer. They’re required to interface with the operating system in any way. Computers would be otherwise useless if there were no storage devices to manage documents, organize files, or access data. From iPads to laptops, just about every electronic device used requires an HDD.

Certain brands sell better quality drives than others based on the materials they use to design their products. The nice thing about hard drives is that computers allow multiple connections at once. When one fills up and there’s no need to replace it, install another. With a USB hub, laptops connect multiple external hard drives as well.