What is SSD and How it works (Simplest Explanation)

how ssd works

Modern Storage devices have evolved gradually with time and when it comes to storing data on your compute, you have two options, a newer, fast, and a bit expensive option which is SSD (Solid State Drive) or an old, slow and cheap option called an HDD (Hard Disk Drive). Well, there are more than two options but those are sub-categories of an SSD only.
Today we will be talking about What is SSD? and how SSD works? in the simplest way possible.

A small history of Data Storage

For a long time, the only reliable way to store data on your PC (Personal computer) was an HDD (Hard Disk Drive) which is the technology that dates all the way back to the 1950s. The first ones were IBM 305s which used to be refrigerator size and could only store a maximum of 3.75 MegaBytes of data each which is just about the amount of data used to store one Photo taken by a Modern Smartphone.


Inside Hard Drives suture a moving arm that writes data on to a spinning disk. Out of all the types of memory in a modern computer, Hard Drives are still the most cost-effective way to store a large amount of data but they are also the slowest. By comparison, SSDs use Flash Memory which involves no moving parts. Flash memory is much faster than a Disk-based memory but it comes with a higher cost than a Hard Disk. Thankfully, Flash Memory technology is evolving, prices continue to drop while Storage sizes are on the rise making SSDs an increasingly viable alternative to Hard Drives.

SSDs are almost 10 times faster than a Hard Drive but are still slower than a RAM (Random Access Memory) which are used as Primary Memory in our computers. But, SSDs have a benefit of working as a long-term storage option just as a Hard Drive even if they can’t currently store as much data and they can’t do it cost-effectively.


There are multiple types of SSDs that you may have heard of. The most common one is the 2.5 inch SATA SSD. These SSDs are the same size as a Laptop’s Hard Disk but are faster than any regular Hard Disk Drive (HDD). These use a SATA data and SATA power connection and does require external power to the drive and uses a 6 Gigabit/second connection depending on what motherboard you are using in your computer and that’s the fastest it can run. In terms of Data-rates, the fastest it can generally run is about 550 Megabytes/second Read and Write although that depends on the SSD that you are using. Some SSDs can push it slightly further but not too much further than 550 to 600 Megabytes/sec.

How SSD works (General Explanation)

Generally explaining, the two main components on an SSD are the Controller and the NAND flash.

The controller is the component that controls the functions of the entire drive. It controls where the data is stored in the drive and it also does more advanced operations like Trash Cleanup and Wear Leveling. Because when Writing onto NAND flash you have to slightly damage it to be able to write to it hence, the read-write lifecycle of the drive is often quoted as how much data can be written to a drive before it dies. So, the life of an SSD depends on the controller as to how it can handle the process of writing onto a NAND flash and maintaining the lifecycle of SSD. The lifecycle of NAND flash is increased regularly with newer and better Controllers.

Now let’s talk about the storage unit in the SSD, i.e the NAND flash. The NAND flash is relatively just a block to store data on and it doesn’t really do much until the controller tells it to do something and it is basically the storage unit in an SSD. The NAND gates that make up the NAND flash are arranged in blocks and you have Data-Lines and Address-Lines fairly similar to CPU Registers and Level-1 Cache if you have ever studied Computer Science in any way.

That’s kind of the basic design of NAND flash and how they are just the storage part in an SSD and nothing complex at least at this level of explanation anyway.

It is quite interesting how data can be stored on chips in place of drives like in a Hard Drive unless you know about the NAND flash as these are made of Transistors and you may not know that Transistors are basically digital switches. These transistors don’t do anything unless the controller tells them to.

So this is the basic functionality of an SSD and the basic components that SSD is made of. There are more complex things that happen in an SSD but that is a more advanced topic that we will cover in the future for our computer enthusiasts.


7 thoughts on “What is SSD and How it works (Simplest Explanation)”

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