HDDs – 11 things you should know

Did you know that HDDs have been in use since the 50s? Or that the first ones were the size of two refrigerators? Or that HDD stands for hard disk drive? Or that over 260 million were shipped in 2020 alone? HDDs are a type of data storage device used in computers systems. In the majority of use case scenarios, they are a vital component of PCs (personal computers). They are home to the operating system and all of the programs and apps are run from stored and loaded from them.

Not only that but all of your personal files are saved to them in the form of a magnetized layer of ferromagnetic material coated to disks. It’s strange to think that your holiday photos have been turned into a sequence of digits which in turn has been turned into a sequence of 1s and 0s that in turn has been turned into transitioning magnetic states.

Hard disk drives are everywhere and you may not even realize just how often you use them.


How do HDDs work?

HDDs are a type of magnetic storage. Inside the casing are disks, sometimes called platters, that are coated in ferromagnetic material. The disk is partitioned down into smaller and smaller sectors spread across the surface of the disk in a sequential manner. Each sector is known as a “bit”, the bits are given a magnetic transition that represents either a 1 or a 0, the sequencing of these bits results in binary code which can be interpreted by a computer to represent everything you can see or do on a computer.

These disks are double-coated stacked, in between the disks is enough space for a “head” to travel back and forth using an “actuator”. The simplest way to visualize this is like a record player. The “head” can move back and forth from the outside of the disk to the center along a single axis. Then the disk spins which gives the head access to the entire surface of the disk.

Their head is responsible for setting the polarization of each bit and detecting the polarization of each bit in order to read and write data to and from the disk. Each side of each disk has its own head and actuator.

By Eric Gaba, Wikimedia Commons user Sting, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11278668

What are HDD platters made of?

The platters themselves are made using a non-magnetic material. This is typically an aluminum alloy, glass, or ceramic material. This platter is then coated using a tiny layer of ferromagnetic material which is as thin as 10 – 20 nm and is covered in a layer of carbon for protection from outside interference. To give you an idea of how small that is, printing paper is somewhere between 70,000 to 180,000 nm thick!

Do HDDs contain toxic materiels?

HDDs are not manufactured today with any toxic materials at all. There is no reason to, as the vital components can be made using completely inert materials, there isn’t any increase in efficiency to be gained y using hazardous substances. Older hard drives could possibly contain older types of solder that contain lead.

Some hard drives create a seal around the platters using various gases. Some use sealed air, it is sealed to protect from moisture and condensation, some use nitrogen or helium. I haven’t found any examples of manufacturers using harmful gasses. For the same reason, I imagine if the job can be done just as well with inert gas then why not use it.

Is HDD volatile or non-volatile memory?

HDDs are non-volatile memory storage. A volatile type of memory is one that requires power to retain information like RAM. HDDs can store information without power for long periods of time. In fact in the perfect circumstances, an HDD could last indefinitely as its magnetic transitions are in a state of balance and require outside forces to influence them. However, entropy might have something to say about that. Typically hard drives mechanical components wear out before the disks themselves are worn. The average lifespan of an HDD is between 8 to 10 years.

How are HDDs connected?

HDDs need an interface to communicate with a computer, they do this through a SATA connection. SATA stands for “Serial Advanced Technology Attachment”. SATA is the older sibling to the now obsolete PATA connection.

You can think of SATA in the same way as USB in that it is an interface that requires a certain type of connection via a certain type of cable. All 3.5″ and 2.5″ hard drives use this connection as standard. Even external drives use this connection they just adapt it to a USB or Lightning Bolt connection in order to be able to connect to the external ports offered by computers. Internally your hard drive is connected via a SATA cable.

How much do HDDs cost?

HDDs vary in cost depending on the size and speed of the hard drive. Not all HDDs are born equal, some are more reliable and fetch a premium, some are faster, some are slower and some even have specific use cases like NAS arrays. With that said the number you will see most often referenced to this, is “cost per Gb”. This refers to the cost per Gigabyte that any hard drive might retail at and can give you a quick indication of how much storage you’re getting for your money.

The range is so wide across the brands and models that an average is almost impossible to estimate but you can expect to pay somewhere between $50 to $170 for an internal 1TB HDD.

What is the biggest hard drive?

The biggest HDD you can buy at a consumer level is 20TB. Just because you can doesn’t mean you should tho. For a long time HDDs were capped at 10TB, this is because the increase in storage capacity did not go hand in hand with an increase in performance, in fact, it was the opposite. The threshold was crossed by manufacturers implementing a new type of HDD technology called “heat-assisted magnetic recording (HAMR)”. These drives are not practical for all situations though and don’t lend themselves to high read/write cycles, and instead are designed for more of a storage solution rather than an operational solution.

Did you know?

Here are some little-known facts about hard drives that may interest you!

The internet is made of hard drives.

That’s right… well kind of, the internet is an interconnected network of hard drives that store and share information. This is both down locally and on servers. Servers are essentially large arrays of hard drives that always have an open connection to them. This means that when you type in your browser “harddrivetalk.com” your browser is asking for the information stored on a server relevant to that particular website. Everything you are looking at on this website is stored on a hard drive in a server and you are simply loading that information into your browser. That is a very simplified way to look at it but that is essentially how it works.

HDDs play an important role in this as they are very good at storing large volumes of data at a low price point and high rates of reliability. Even though they have been around since the 50’s and in use in consumer electronics from the 80s they have seen little in the way of leaps forward in innovation in recent years however they are still able to keep up with the demands of modern technology and some companies are even investing in developing the technology further to produce higher capacity solutions to meet the demands of modern-day data requirements.

Hard drives can work upside down.

Hard drives can work upside down, on their side, on their end, in fact, they can work in any axis so long as they are not tilted. This is because they are sensitive to external forces interrupting the centrifugal forces exerted by the spinning disk. You can read more on this here in our article on the subject. Can you use a hard drive upside down? 5 reasons why you shouldn’t

Hard drives have been around since the 50s.

IBM invented the hard drive and released them in 1957, however they were not the hard drives you see today. The first one to market was the size of two refrigerators! It wasn’t until the late 80s when HDDs became a staple of the computer, during the 80’s they were an external accessory for storing data. it was around about this time that the 3.5″ format and 2.5″ format became the pinnacle in performance and efficiency and soon became the standard.

The first-ever hard drive was 68 feet cubed (or 1.9m3) in volume which was refined until it resembles the drives we know today as small as 2.1 inches cubed (or 34cm3) and while the physical size has decreased by a factor of 56000:1 the capacity has increased by a factor of 5,333,333:1 from 3.75megabytes to 20terabytes!

Hard drive sales are in decline.

Despite huge declines in sales since the record high in 2010 HDDs still have their place in modern computing. They are still the most efficient storage solutions for enterprise levels of storage and make up a huge majority of most data centers’ capacity. Typically they will be used in conjunction with the faster SSDs of today in order to prove the advantages of both to the end-user.

While smaller drives have reached a plateau of usability and are more and more often being replaced by SSDs in the consumer market. The enterprise market is still growing and HDDs are an effective solution to the ever-increasing creation of and demand for data. So although they are finding a new place in the world of computing they are far from obsolete and manufacturers like Seagate are allocating huge resources to developing HDDs further with predictions of increasing HDD capacity to 50TB by 2026 and as large as 100TB by 2030.