Computer Storage

Computer storage units have developed significantly in the past years. The development has taken place on several levels, such as the available space for storage, the storage units themselves and the ways of communicating with the rest of the computer components to carry out various tasks.

The technologies in which storage units work have also evolved, which has contributed to a drastic acceleration of the processes of reading and writing files. Faster reading and writing technologies facilitated a large number of tasks such as data processing and loading, which contributed to an improved computer experience.

Any computer user deals on a daily basis with different forms of storage units used in the computer, due to the different and sophistication of these units, and therefore it has become important to identify the features of each one so that the user can deal with them in the best way that suits him.

In this article, we explain to you the different types of storage units in the computer and the optimal use of each type.

computer storage units

Before starting to explain the storage units in the computer, it is important to understand the process of measuring the size of files, which depends on several basic units.

The order of measurement of volumes from smallest to largest according to the binary system is:

  • Bit: The smallest unit of storage in a computer, and it is often used to record a value equal to 1 or 0 only. Bits are mainly used to record values​​related to the operation of computer components in terms of turning them on or off.
  • Byte: It consists of 8 bits, so you can register 8 values ​​in addition to the possibility of registering one character.
  • KiloByte: equals 1024 bytes and is denoted by KB.
  • MegaByte: Equivalent to 1024 kilobytes and denoted by MB.
  • GigaByte: Equivalent to 1024 megabytes and denoted by GB.
  • TeraByte: Equivalent to 1024 gigabytes and denoted by TB.

There are larger units for measuring the size of giant files such as exabytes and zettabytes, and they are based on the same binary multiples system as before.

Larger units of measurement are common in computers that specialize in data analytics and giant servers.

Important note: rely Operating systems measuring storage units in decimal or Decimal, in which the size of the units increases in decimal, while companies that design storage devices rely on calculating the space of their devices in the binary system.

The difference between the systems can be seen when purchasing a 1 TB storage unit, but the operating system shows only 931 GB.

Note: Many computer users use the term “computer storage units” to refer to the storage areas that were addressed above, and they use the same term to refer to the devices or media used in storage, so you will find that we sometimes use the same term to refer to storage devices in the computer.

Types of storage units in a computer (storage devices)

Computer storage devices or computer storage media is any device that can be used to store files on a computer, either permanently or temporarily.

Types of storage units in a computer (ie, storage devices in a computer) can be divided into two main types:

1. Main volumes

Basic storage units mean any unit on which files can be stored temporarily, for a short period of time while using the computer,

These units are not completely user-controlled and are used to store simple commands and programs.

The most famous primary storage unit is random access memory or random access memory or known as RAM, and it is known to be the most important volatile storage unit, or that saves data temporarily until it is turned off.

2. Secondary volumes

Secondary storage is any storage device on which files can be stored permanently and that can be installed inside or outside a computer.

Secondary volumes are also known by several other names such as:

  • Storage device
  • Backup Storage device
  • Internal Storage device
  • External Storage device
  • Portable Storage device

The difference between the main and secondary storage units is that the first is used by the computer to communicate with its components and record operating commands, while the second is used by the user for the purpose of recording well-known files such as photos, videos and games.

In this article, we will discuss the storage units in the computer that belong to the type of secondary units. As for the main units, we will address them in another article, since dealing with them is fundamentally different from dealing with secondary storage units.

Secondary storage units in a computer

For two decades the world has relied on floppy disks, or Floppy Disk, to store files. For a long time these tablets did their job perfectly, but they were not suitable for the future.

Floppy disks have a short shelf life and small storage areas, which contributed to their extinction after the release of newer storage methods.

Currently, there are four basic types of volumes where your files can be stored:

  1. Magnetic storage devices.
  2. Solid-state storage devices.
  3. Optical storage devices.
  4. Portable storage units.

The four types fall into units that occupy different classifications in terms of connectivity, technology used to read and write data, and others.

Here is a preferred explanation of each type and its subtypes:

1. Magnetic storage units

Magnetic storage is any storage unit that uses magnetic patterns to store data. The most popular storage units based on this technology are floppy disks and hard disk drives (HDDs).

Hard disks HDD is known by more than one name and abbreviation in the field of computer, including:

  • Hard Disk Drive
  •  HD
  • HDD

Hard disk drives are storage units on which data is stored non-volatile or permanently. The term non-volatile refers to volumes that maintain stored data after they are turned off.

A hard disk has four main components:

  • Multiple hard disks for data storage.
  • Spindle to rotate discs.
  • Arm to read and write data.
  • The operator and controls the actions of the reading and writing lever.

Here is an image showing the components of the hard drive:

Hard disks are used in a large number of devices other than the computer, which led to the emergence of different types of them. Companies have developed several types of hard drives, each type providing customized performance for these devices.

In this article, we will mention the most popular types of hard drives for computers, which are provided by two companies:

  • Western Digital
  • Seagate

First, the most important types of hard drives provided by Western Digital

1. WD Black Hard Drive

Black hard disks are designed to provide the highest speed in reading and writing data, but they have annoying defects, the sound of hard disks is high and their temperature is high compared to other types.

In the past, it was recommended to install the operating system and basic software on a black storage disk because of its speed in reading and writing data. Currently, most users turn to installing the operating system and software on SSD storage units, as they are faster than black disk drives.

2. WD Green Hard Drive

Green hard disks are primarily intended for storing data in an energy-saving manner. These units require less energy than other units to perform their function, which helps not to overheat too much. On the other hand, these units are the slowest among all solid storage units as they provide low speeds to read and write data.

Western Digital no longer manufactures green hard drives because users are dispensing with them, although the company still uses green to distinguish hard disks with lower speeds in reading and writing data and rationalizing energy consumption.

3. WD Blue Hard Drive

Blue hard drives are the best choice in today’s flash drive storage units. The units provide good speeds for reading and writing data without reaching high temperatures or making annoying noises. Blue hard disks have replaced green disks for storing regular files.

4. Other colors hard disks

Western Digital produces hard drives in other colors for other categories and uses. The company has allocated the red color to discs intended to work in networked storage devices and companies.

Second, the most important types of hard drives provided by Seagate

1. BarraCuda Hard Drives

Barracuda drive offers features similar to the blue hard drives offered by Western Digital.

2. FireCuda SSHD

Firecoda is a drive that contains hard disks and hard disks that work together. These disks integrate hard disk technology with hard disks. The combination of the two technologies provides outstanding performance in dealing with files that are used continuously, such as programs and operating system files.

Seagate offers other storage hard disks that are used in networking and monitoring devices such as:

  • IronWolf unit.
  • SkyHawk unit.

Now, here are some of the important questions about solid state storage:

What is the largest solid state storage in the world?

Currently, hard drive manufacturers provide the world’s largest storage unit in terms of space. Western Digital and Seagate offer storage units of up to 14 TB for normal use and 16 TB for security monitoring systems.

What are the sizes of hard drives?

Hard disks are available in two sizes:

  • 3.5 inches, which is the size designated for the units that are installed inside the computer.
  • 2.5 inches, which is the size designated for units designated to be installed inside laptops or portable storage units.

Both sizes have the same advantages and disadvantages and both depend on the same method of connection to the motherboard.

How are hard disks connected to the computer?

Today, hard disks rely on the famous SATA interface that most computer storage units rely on. The SATA interface consists of an input dedicated to transferring and exchanging data, and another input for power delivery.

What are the most common causes of hard disk failures?

  • Surge or power outage.
  • Drive overheating.
  • The drive has been exposed to water, spills, or moisture.
  • The hard disk fell on solid ground.
  • Improperly shutting down the computer.

The previous reasons may expose the hard drive to damage in whole or in part. Partial damage means problems or difficulty reading and writing data saved on one of the drive’s disks.

2. Solid-state storage devices

SSDs or Solid State Drives are the fastest storage units in the storage industry today. Unlike hard disks, the reading and writing technologies used by hard disk units vary.

SSDs do not rely on rotating disks but rather on semiconductor chips to write and read data. These chips are divided into pages on which the data is stored.

What are fixed volumes made of?

The main components of fixed storage units are:

  • A controller (its role is to control the way flash chips are written).
  • NAND flash memory chips (its role is to store files and data).
  • Random memory dedicated to speed up the process of reading and writing files (not found in economic volumes).

SSDs do not have moving parts, so they can run much faster than hard drives.

The most important features of SSD units

  • High speed reading and writing files.
  • Less power consumption.
  • Shock resistant.
  • It does not heat up significantly compared to moving discs.

What are the main types of SSD storage?

SSD storage types can be categorized based on several factors such as:

  • Computer interface.
  • computer delivery method
  • the size

First, the types of SSD storage units according to the computer interface

Hard disks rely on more than one interface, unlike their hard disk counterpart, which currently depends on a single interface, which is SATA.

a) SSD storage with SATA interface

The SATA interface is the same interface that hard disks rely on to connect to the computer. The SSD storage units that work with this interface are the oldest in this class of these units, because they are the first storage units that relied on SSD technology.

SATA-powered SSDs can reach read speeds of up to 570MB/s, which are five times faster than hard drives.

These units enable you to open the computer in about 15 seconds, and they can read and write huge files within a few moments.

The most common type of SATA SSD in laptops is 2.5 inches.

b) SSD storage with NVMe interface

An NVMe interface allows SSDs to reach faster than SATA speeds.

NVMe SSDs can read files up to 2,600MB per second, which is five times faster than SATA SSDs.

NVMe SSD storage is ideal for users who work with large compressed files.

Second, the types of SSD storage units according to the method of connection to the computer

When SSDs were released from the SATA system, their connection method changed to include two connection methods, both of which provide important advantages in terms of speed and power consumption.

a) Connection via M.2 Slot input

M.2 port helps SSD storage reach faster read and write speeds, SSDs that rely on M.2 port and NVMe interface can read and write data at speeds of more than 2,600MB/s.

An older version of M.2 supports SATA hard drives, but current versions support NVMe.

b) Connection via PCIe Slot

PCIe port is the well-known port for installing graphics units, but several years ago, storage units appeared that take advantage of its enormous capabilities.

When the motherboard does not have an M.2 port, NVMe SSDs are connected via a PCIe card with an M.2 connector.

PCIe hard disk drives provide the highest read and write speeds for this type of unit. The data read and write speeds for units powered by this port are up to 5000MB/s.

To make the most of the PCIe ports, the version of the port on the motherboard must match the version that the module is based on. There are several versions of the PCIe port dedicated to connecting hard storage units, the latest and fastest is version 4.

Important note

There are two forms of PCIe input:

Figure 1: The port that users are used to installing additional GPUs and APUs.

PCIe port for installing the GPU and additional units, including the SSD card.

The second form of PCIe port: It is a port dedicated to installing M.2 SSD storage. The explanation of this port is a little complicated as it is an M.2 port, but it supports PCIe technology when it is installed with a storage that supports this technology.

An image to show the entrance to the installation of M.2 SSD storage devices that support PCIe technology.

Third, types of SSD storage units according to size

a) 2.5 inch storage units

The 2.5-inch size is the traditional size for SATA-only hard disk drives. These units are used either in laptops or desktop computers, and they are also used in the manufacture of portable storage units.

b) M.2 . volumes

M.2 or the industry standard M.2 sizes is a common standard found in laptop components, this size was commonly used in the manufacture of wireless calling cards or Wi-Fi cards found in laptops.

Contrary to popular belief, there are several sizes that fall under the M.2 storage standard. Hard disk units use two sizes of them:

  • Size number 2280 is the size commonly used in modern desktop and laptop computers.
  • Size number 2242, which is the size used in relatively old laptops and is no longer common today.

There are other sizes for the M.2 standard, but they are not commonly used, such as 2280 and 2242. Below is an illustration of the different sizes of the M.2 manufacturing standard, knowing that the unit number consists of the unit width and length.

3. Optical storage devices

Optical storage units are referred to by more than one name, such as:

  • Disc Drive
  • Optical Media
  • Optical Storage
  • Optical Disc Drive
  • Optical Disk

An optical disk is any storage disk that is read using laser assembly technology. In the past, hard disk space did not allow to save all files, which made ordinary users and companies turn to storage on disks.

Once upon a time, every computer contained an optical drive, or optical drive.

Optical reading units whose main goal was to read discs made by large companies such as software and media discs. Later, devices appeared that allowed the average user to save his files on discs sold in different sizes and for different purposes.

The beginning of the discs was with a CD or a Compact disc, and there were discs dedicated to songs and others for larger files.

The disc dedicated to songs was small in size and space, and unlike the discs dedicated to larger files, the discs ranged in size from 650 to 700 MB.

Optical storage is developing later in terms of storage technology and disc size with the advent of DVD or Digital Video Disc technology,

The discs available for DVD storage range in size from 4.7 to 8.5 GB.

We have reached the latest disc storage technology with the release of Blu-ray discs that reach huge areas. Blu-ray discs provide space of 25 GB and sometimes 50 GB for discs that allow storage on both sides.

Why say relying on disks to store files?

proliferation platforms such as Netflix and the ability to download content from the Internet contributed to the waning popularity of optical media, and the low price of USB units and their ability to store more files led to less use of optical media as a storage medium.

4. Portable storage units

Mobile (also called portable or external) storage units fall into two categories:

a) Mobile portable storage units

There are mobile storage units that rely on hard or fixed storage disks that are wrapped in a plastic cover to protect them and facilitate the process of moving them, unlike regular mobile or fixed hard disks. Connecting portable storage units is often through USB ports.

Mobile storage is based on the fastest version of USB ports to transfer files as quickly as possible and save energy.

Portable hard disk drives are less expensive than their hard disk drives because the hard drives offer faster data read and write speeds.

b) Optical storage units or USB Flash drive

Optical storage units (which is called among many names) are the smallest storage units in the computer. These units depend on hard disk technology to read and write data and are connected to the computer through the USB port.

Computer users used to rely on optical storage units to store small files, but this has changed recently. Early versions of optical storage units provided relatively small areas, but now amount to 1 terabyte.

Increasing the space of optical storage units led to reliance on them to store larger files, but storage is their only function,

Although these units rely on hard disk technology to read and write, they do not provide the same speed for several technical reasons.

In general, optical storage is an excellent solution for file sharing and quick storage tasks and is the cheapest storage unit.


In this article, we discussed the most important computer storage units that most users rely on to store their important data.

Most users currently rely on an SSD unit to install the operating system and basic software, while they rely on hard disk drives to store their files.

Do you follow the same method? Share your opinion in the comments about the fastest storage unit you have used and its specifications


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