HARD DRIVE
Let's go with the Hard Drive or mostly known as HDD. These drives uses a magnetic circular plate called platter. If this is the first time you have heard of it, yes, it uses magnet and it sounds weird because how can a magnet manage to store my documented projects that are nearing deadline, all the songs on my playlist(Nobody plays all of the songs saved in there, you just choose a few and you play it again and again until you don't want it anymore and you choose another few) and all this unfinished games because of school or work? You can think of it as nail(projects), tacks(songs) and paper clips(games). If they will be processed in the hard drive, data can be magnetized(saved/stored) or demagnetized(removed/deleted) from it.
As I've said, drives can manage to save and open it again. We took up the saving part and now, how can it find the data that I want to get if it is all scrambled up in the magnet. The thing is, it is not scrambled up, Those data are stored in an orderly pattern on the platter(the magnet disk we're talking about earlier). Data is stored on a circular path(I already said it was a circular plate in case you are wondering why) and this paths is called tracks. Then it is broken up to smaller portions and these portions are called sectors(ever got the "bad sector" issue, yeah, that's it). Whenever you are trying to store a new data, it would be looking for a free sector and puts it there and the one doing this is the actuator. This actuator has a mechanical arm that moves according to what data you are trying to access and where it is located and a head that access the data from the platter. Now, the thing is it ain't forgetful as most of us and it knows where it was stored and what was stored there. Hope you get the idea of what a hard drive is and what it does and how it is being done.
SOLID STATE DRIVE
On to the next would be the Solid State Drive or the SSD. These kind of drive was introduced way back on the 1970's. It may even be older than you but you might never heard of it or maybe you heard or read about it but never actually used of it. How come? We will answer that after we discuss what this SSD is. You can think of the SSD as your USB flash drive. Solid State Drives are called that because they don't rely on moving parts(actuator and platter for HDD). It has the same read and write feature but in different method. The data that will be saved in an SSD is being stored in a NAND flash memory. This type of memory is non-volatile, it means you even if the power was shut off, the saved in the memory will still be retained.
The process of writing a data on an empty space would be quick but updating it would be much slower. We'll discuss this thing further. NAND groups the stored data by blocks then read, delete and write at it depending on the process needed. Since this is a microchip, it involves electrical charges whenever it process. Let's say that the data are the books and the blocks are the shelves. You give in more effort and stress in changing or updating the books in the shelf rather than just putting it in there. Same goes for the process of updating and storing data in the NAND. Whenever the data is being updated it uses more voltage and this is not good for the NAND(same goes for humans, avoid stress as much as possible, it ain't good on you).
If you're still wondering how complicated the process of the updating these data, we'll dig in a bit deeper. Although this may be more on a technical side but we'll talk about it as simple as we can. First, stored data are being grouped up as blocks in the SSD. Storing data in an empty drive, we have our data A and data B to be put in the block A(easy part of the process). Now, if we are going to update data A and change it, it would have a replacement data A(updates) and stale data A(previous data). So now our block has data A(stale data), data B(retained data) and another data A(updated data). We've said earlier that updating needs much more voltage than just adding data so this is what the NAND memory do. The old data will not be updated until the whole block is erased(as we've said earlier, it is easier to just add data rather than to update it), so now we will move the all the data in the memory, read and write it on another block. We now have have the data A(updated data) and data b(retained data) in block B because we removed it from block A, then block A will now be erased. I know, it's a bit complicated but that's what happens.
We now have the basic knowledge of what and HDD and an SSD is also how they work and how they process the data within them. The question right now is, what should computer drive should I choose right? You can find the comparison of these drive here -The Solid vs The Hard (Comparison between the Solid State Drive and Hard Drive) and this will help you understand further the
