Hello, in this article, I will try to explain the differences between HDD and SSD components, which are storage units in technological devices such as phones and computers that we use daily, and the basic working principles of these storage units.
You can click on the following topics to jump to the section where I explain them:
What is the Function of Storage Units?
What is an HDD and How Does it Work?
What is an SSD and How Does it Work?
What are the Differences Between HDD and SSD?
What is the Function of Storage Units?
In this article, I will discuss HDD and SSD components, which are storage units. To understand what storage units do, we need to know this basic principle: All programs, photos, videos, games, and everything else inside computers, phones, and other technological devices are composed of just the numbers 0 and 1. A simple example of this is the photos stored on our technological devices. As we know, photos are made up of pixels. Our computers store all the pixels in a photo using a series of 0s and 1s.
(This example shows the 0 and 1 values of a pixel in an RGB photo)
HDD and SSD units store these photos by recording the 0s and 1s from our series of 0s and 1s using their own methods. Thus, our photo, made up of 0s and 1s, is safely stored in our storage unit.
What is an HDD and How Does it Work?
HDD, which stands for Hard Disk Drive, was used to replace punched cards that stored necessary information before its existence. In 1956, IBM used the first hard disk, called the IBM 350, which had a capacity of 3.75 MB, in its IBM 305 RAMAC computer. Since then, HDDs have replaced punched cards.
HDDs store information using microscopic magnetized metal pieces. Nowadays, HDDs magnetize in two different directions: N (1) and S (0). Therefore, HDDs must be used and transported very carefully because even the smallest electromagnetic change can alter the magnetic directions on the disk, leading to data loss. So, how does an HDD read these microscopic magnetized pieces?
The above image shows a highly magnified example of the needle that reads the disk inside an HDD. This needle consists of two parts: a read head and a write head. When we want to access something from the storage unit, the read head of the needle quickly reads the magnetic values on the disk and sends them back as 0s and 1s. The write head, which contains a coil, is used for writing. When a signal arrives at the write head, it operates based on this signal. If a 0 bit needs to become 1, the magnetic field generated by the coil changes the S direction to N. If the bit remains the same, there is no change because the magnetic field is already aligned with the bit to be written. The disk continues to spin at high speed during these processes, allowing data to be read or written quickly.
What is an SSD and How Does it Work?
SSD, which stands for Solid State Drive, was first introduced in 1991 by the company formerly known as SunDisk, now SanDisk. This SSD was used in IBM's ThinkPad laptop and had a capacity of just 20 MB.
The working principle of SSDs is very different from HDDs. While HDDs store information in electromagnetic pieces, SSDs use much smaller semiconductor cells. These semiconductor cells vary in structure depending on the type of SSD. There are three types of SSDs: SLC (Single Level Cell), MLC (Multi Level Cell), and TLC (Triple Level Cell). SLC SSDs can store only 1 bit per cell, so they have less storage capacity but are much faster and more secure. MLC and TLC SSDs store 2 and 3 bits per cell, respectively, and operate slower than SLC cells. The more bits a cell holds, the slower the SSD, but the storage capacity is much greater. Therefore, MLC and TLC SSDs are used in everyday computers and phones due to their cost-effectiveness and high storage capacity. But how are bits stored in these cells?
The image above represents the inside of a TLC SSD cell. Eight different levels are used to store 3 bits. Bits are recorded on the SSD based on the level of fullness of these 8 levels. When an SSD performs a write operation, it traps the electrons in the cell at the desired level to represent the desired bits. For example, in the image above, the electrons are trapped at level 5, resulting in a value of 011 for that cell. The trapped electrons remain there as long as we want, ensuring our data is stored. If we delete an application or photo stored on the SSD from our phone or computer, the electrons in the cells of the SSD where the application was located are released. Since these processes occur almost at the atomic level and without any mechanical operation, they work very quickly and silently.
What are the Differences Between HDD and SSD?
Now that we understand the working principles of SSD and HDD, we can discuss their differences and where it makes sense to use each.
- When comparing the working speeds of HDD and SSD, SSD is faster because it contains no mechanical parts and all operations are performed at the electron level. HDDs, on the other hand, are slower compared to SSDs because they contain mechanical parts such as disks and read/write heads.
- HDDs are noisier compared to SSDs due to the presence of mechanical parts.
- HDDs are cheaper compared to SSDs.
Instead of saying which is better or worse, it makes more sense to discuss where each would be more useful. While it's clear that SSDs are much more efficient, price also comes into play, and everyone's choice depends on their budget. If you use your computer primarily for saving files such as photos and videos and don't use your computer regularly, an HDD might be the right choice for you. If you don't want to spend a lot of money and don't expect high performance, an HDD is the most logical option. In the year I am writing this article, 2020, a 1 TB HDD costs the same as a 256 GB SSD, so an HDD would be more budget-friendly. However, if you use your computer regularly, I highly recommend using an SSD because HDDs can significantly slow down your daily tasks and cannot keep up with the speed of SSDs. Although SSDs are still more expensive than HDDs, they are becoming cheaper and more widely used. The transition from HDD to SSD is similar to the transition from punched cards to HDDs. Hopefully, in the near future, we will use storage units that are much faster than SSDs in our daily lives.
I hope this article has been informative for you. If you find any incorrect information in my article or if you have any questions, feel free to contact me via email. You can find my email address above.
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