If you're buying a new computer or upgrading an old one, you might get an SSD ( Solid-State Drive) instead of a traditional hard drive (HDD). Switching from an HDD to an SSD is one of the best upgrades you can make to a PC, as it will greatly improve performance.
Why? What makes SSDs so groundbreaking?
Below we will see what exactly SSDs are, how they work, why they are so useful, but we will also talk about the most important disadvantage of SSDs. So if you want to change your disk(s) and are thinking about SSDs, it would be a good idea to read the article.
Computers and memory
To understand how SSDs work and why they are so useful, we first need to understand how computer memory works. A computer's memory architecture is divided into three phases:
- The cache
- Memory
- The data storage disk
Each of these features serves important functions of your computer.
Cache memory is the internal memory unit. Your computer uses cache memory as a kind of clipboard for calculations and data processing. The electrical paths to cache memory are the shortest, making data access almost instantaneous. However, cache memory is very small, so the data it contains must be replaced constantly.
RAM (Random Access Memory) is the part of your computer that stores data related to programs and running processes. Accessing RAM is slower than accessing cache memory, but by a negligible amount. As with cache memory, the data it contains must be cleared continuously, usually with each restart of the computer .
The hard drive is where permanent storage happens. It's where all the programs, settings files, documents, music files, movies, and everything else on your PC is kept. If you try to open a program, the computer has to load it from your hard drive and then from RAM.
The most important thing to remember from all of the above is the vast difference in speed between the three features. Cache memory and RAM operate at speeds measured in nanoseconds, while a traditional hard drive operates at speeds measured in milliseconds.
In essence, how fast a computer is is relative and depends on the bottleneck: no matter how fast all its features are, a computer can only load and store data as fast as its hard drive can handle it.
This is where SSDs come in. Traditional hard drives are very slow compared to cache and RAM, while SSDs are faster. This significantly reduces the time it takes to load various programs and processes and makes your computer much faster.
How do Solid-State Drives work?
Solid-State Drives serve the same purpose as regular hard drives: they store data and files for long-term use. The difference is that SSDs use a type of memory called “flash memory.” It’s similar to RAM, but unlike RAM, it doesn’t have to clear its data every time the computer starts up. The data on an SSD still exists even when it’s lost.
Now if we open a regular hard drive, you will see that it contains magnetic platters with a stylus. Before the stylus can read or write data, the platters must be brought into the correct position.
On the other hand, SSDs use a grid of electrical cells to quickly send and receive data. These grids are divided into sections called “pages” and data is stored there. Multiple pages together form a “block.”
SSD is called “solid state” because it has no moving parts.
SSDs can only write to empty pages that exist within a block. In regular hard drives, data can be written anywhere and at any time on the “platter.” This means that data can be easily overwritten. SSDs cannot directly overwrite data on individual pages. They can only write data to empty pages that exist within a block.
So how do SSDs erase data? When some pages in a block are marked as unused, the SSD stores the entire block in memory, erases the entire block, and then restores the data from memory to the block. You should be aware that erasing a block does not necessarily mean that the data is completely erased.
SSDs slow down over time.
On a new SSD, the blocks are loaded full of empty pages. So when you try to write new data to the SSD, you will notice amazing write speeds. However, as more data is stored, and the empty pages run out, you will have empty random pages that are not being used and will be scattered throughout the blocks.
So as we said above, since the SSD cannot directly erase a single page, every time you want to write new data when the disk is full and there are few empty and scattered pages in the blocks, the SSD will have to:
- Find a block with several pages marked “unused”
- Record which pages in this block are necessary
- Delete each page of the block
- Reposition the necessary pages in the new block
- and finally use the empty pages to write the new data
So, in essence, once you've used up a lot of the empty pages on your SSD, your drive will have to do the whole process above every time new data needs to be written. That's how flash memory works.
Despite this, SSDs are still much faster than regular hard drives.
The disadvantage of SSDs
Now that we have seen how a Solid-State Drive works, we can also understand one of its biggest drawbacks: flash memory can only perform a finite number of writes before it “dies.”
So, SSDs have a finite number of writes. However, this does not mean that a Solid-State Drive will not last a long time.
Having read the above and if you want to buy an SSD, ask your supplier about the average lifespan of the Solid-State Drive you are interested in, or simply look at the warranty.
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