Ever Wondered how Hard Disk Drives make use of magnetism to store information.

3년 전

Hello steemians, its such a fantastic day and another amazing time to explore the world of science and technology.

Everything just seem to be happening at the same time for me, with work getting busier and more stressful and having to joggle many activities and professional examinations coming up, I just have to take a pause to get some balance.

In the midst of All this craziness the unthinkable happened to me on the 15th of this month. while I was preparing to go meet up with my friends to go watch the World Cup Final (France vs Croatia), I hurriedly left the house and left my hard drive on my bed forgetting that my little cousins had come visiting.

my 1terabyte LG external hard drive photo taken by @steematlas using infinix hot 4

After watching the exciting world cup final with my pals, I got back home with the excitement of the whole football experience only to get the shocker of my life. My little cousins had turned my room upside down, which was not a big deal until I realized amongst other things they had played with was my 1TB (1terabyte) LG external hard drive. The first thing I did was immediately connect it to my laptop while I silently prayed the drive was still intact, but unfortunately for me the worst had happened my external hard drive had been damaged and Everything I had on the drive like my applications, YouTube tutorial videos, music, HD movies, games, photos and important files had all disappeared.

Have you ever experienced that moment when your brain just shuts down and you just become completely speechless?

Well that was exactly what happened to me at that point, Well I tried to repair and recover some files but it was futile and I just had to console myself and kiss my 1TB external hard drive goodbye. In the course of researching on how to repair my hard drive I stumbled on what I would be sharing today?

So sit back and relax while I share with you the operations of an External Hard Disk Drive (HDD)…


A hard drive is a Superb piece of hardware that stores digital files such as document, pictures, music, videos, application preference, programs. A hard drive could either be a hard disk drive (HDD) or could also be a Solid State Drive (SSD). These two kinds of hard drives achieve the same Goal but they carry out their operations in completely different ways. I would be focusing on HDD on this particular post, SSD is a topic for another Day.

A hard drive could easily function as an internal drive or external drive. It is important to point out that internal hard drives can easily be converted into an external hard drive using hard drive enclosure. So basically an external hard drive connects to a computer externally rather than internally either by the use of USB, FireWire, eSATA or wirelessly.

An External hard drive is an absolutely amazing tool for sharing very large files and using them can ultimately save you the stress when moving files from one computer to another and due to their very large storage capacity they are very effective when it comes to the storage of backed up files. Users make use of them for safe keeping of their important files so they would not risk losing all their files for cases where the original files get corrupted or accidentally deleted.

An average laptop is manufactured with limited storage space like 500GB or less so External hard drives provide an Easy and efficient way to expand existing storage for cases where the storage capacity of a computer is not sufficient for what is required by the user and the computer starts acting sluggish. Users simply just get a suitable external hard drive and transfer some heavy files to it so as to free up space on the computer so that it can perform optimally without the need to open the computer to expand.

It does not come as surprise that the use of external hard drive has increased over the years as a result of the large amount of additional storage space it provides users as well as how portable and easy to use it is. Users can easily have access to a very vast number of files without the stress of having to move around with their computers.

External hard drives are quite superb for people who would do a lot of moving around and would require their files handy at all times. Hard drives come in different shapes, Storage capacities, designs, and prices while some external hard drive function by getting their power from the computer through the data cables and some others would have to be connected to an AC source to get its power before it could be used. The type of storage unit required is based on the needs of the user.

Now Lets take a closer look at a Hard disk drive (HDD)

The most important part of the HDD is the Platters, they could either be made from ceramics, aluminum or glass. Information are stored magnetically in binary form on one or more shiny silver platters and there is a central spindle in place that facilitate the rotation of the platter at high speed. To record and store information on the platter there is a read-write head connected to the end of a Read-write arm in the HDD, this read-write head is a tiny magnet that moves back and forth the platter, this movement is responsible for storing and recording information and is facilitated by an Actuator.

For magnetization and demagnetization to take place the materials used to make the platter are coated with a thin layer metal and depending on the size there can be one or more platters, such that each platter has two read-write heads, where one reads the top surface while the other reads the bottom surface. For Bigger drives one platter is not enough so to tackle this several platters are stacked on a central spindle such that there is a small gap between each of them and the read-write heads can easily have access to any part of the platter. However, to reduce wear and tear there is a layer of fluid or air to prevent this.

Data is transferred within the HDD using a flexible connector and there is an electronic circuit that effectively controls the operations and the flow of data to and from the platter in the HDD.

Take a look at this simple illustration

Ordinarily if you pick up iron nails, they are not magnetized but then when you constantly rub them with a magnet consistently, those demagnetized iron nails become magnetic and can now stick to one another. If you observe these magnetized nails for a while you would realize that the nails would stay magnetized until they are demagnetized again

By now you would be wondering if there are nails in a hard drive… not at all

Hard disk drive typically function based on the principle of a magnetism, it is so important to the operation of an HDD such that when power is turned off from the drive the information stored is still intact and can be accessed anytime.

If you take a look inside a hard drive you would notice a large shiny circular plate of magnetic material known as a platter. Depending on the storage capacity of the hard drive this platter is divided into several billions of tiny areas and just like the nails I illustrated above each one of these areas can be magnetized and demagnetized. For a computer to save a number let’s say 97, the computer stores the number as 001100001 which is a binary number.

Numbers are stored in a computer as patterns of binary digits such that When they are magnetized they store a 1 and when they are demagnetized they store a zero. When the power is switched off the information stored is still intact. For effective filing the data are stored on each platter in an orderly pattern such that each bits of data are arranged in tracks which is a concentric circular path, these paths are further broken down into sectors.

For the drive to know the size of free space and the used space, it stores a map of sectors such that when new data is to be stored on the drive, the drive would check the map to ensure there is free space available then it allocates the space and the read-write head can move across the platter to the allocated spot and store the data.In the same way when the drive needs to locate a file on the drive it checks the maps and gives the read-write head instruction to go to the exact location to read the information and make it available to the user. Different operating systems refers to this map using different terms for example in Windows this map is referred to as the File Allocation Table (FAT).

The circuits built within the HDD known as the controller is responsible for determining the right tracks that would be used for reading or writing and when it is connected to a computer it continuously does a parallel to serial streams of data conversion which would be read or written on the disk as the case maybe.


A hard disk drive is a superb and handy piece of technology which has a high capacity to store a lot of information at relatively low cost. Ordinarily an HDD could easily work without any issues for decades but just like any other piece of technology it has its own disadvantage. Due to the several intricate moving parts that make up the HDD they are prone to head crashes due to mechanical damages or sometimes dusts or dirt on the platters can hinder it from performing optimally, hence HDD require proper care or users might lose their files permanently.

Problems like reliability, power consumption, access time associated with using a Hard disk drive can easily be solved using a solid state drive which makes use of flash memory chips as a replacement for the spinning magnetic platter. Hence there are no moving parts in an SDD thereby making them faster and more reliable. This makes them the perfect choice for users that require faster performance, reliability and are ready to spend more money.

However due to the cheaper cost, hard disk drives are still very popular and widely used by users that require large storage capacity but don’t have so much to spend and don’t care about the speed.

So If your computer is acting sluggish due to insufficient space, I think it is a good time to get yourself an external hard drive and It is always really wise to buy an external hard drive that exceeds what you need at the moment just for futuristic purpose.

My next post I would focus extensively on the operation of a solid state drive (SSD)


how do hard drives work

what is a Hard drive- types and functions

Functions of Hard drives

Hard drives

How Hard disk

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I'm quite unfamiliar with most of the part discussed in this article, but looking at the way data was stored, is that the exact reason why data can be destroyed by using a magnet? What about SSD? They are much durable than HDD. Does it operate on the same principle with an HDD?


The mere fact that HDD works on the principle of magnetism Already makes them prone to being corrupted by a magnet..... But for this to occur a really Strong magnet would be required

Secondly SSD works on a completely different principle: i would write about the principle of SSD in my next article So watch out...

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I think HDDs are dying; we are entering into the era of SSDs :)
I'd like to ask a noob question, is there a likelihood of altering a content of an HDD through placing a permanent magnet right close to it?


There's no doubt SSDs are taking over But HDDs are still quite popular and still widely used But SSDs would fully take over when they become more affordable...

Secondly Strong Magnets Placed close to an HDD can corrupt the drive: Although small magnets would have no effect on an HDD..

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Thank you too.

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