What Is HDD?
A hard disk drive is a data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are padded with magnetic heads usually arranged on a moving actuator arm which read and write data on the platter surfaces.
Data is accessed in a random access memory meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. STDs are a type of non-volatile storage retaining store the data even when powered off. Introduced by IBM in 1956 H CDs became the dominant secondary storage device for general-purpose computers by the early 1960s.
More than 200 companies have produced as CDs historically though, after extensive industry consolidation, most current units are manufactured by Seagate, Toshiba and Western Digital. The primary characteristics of HDD are it’s capacity and performance capacity specified in the unit four fixes corresponding to powers of thousand of 1 TeraByte drive has a capacity of 100 gigabytes.
Where 1 GB is equal to 1 Billion bytes. The two most common form factors of hen CDs are 3.5 inches for desktop computers and 2.5 which primarily for laptops. HDDs are connected to systems by standard interface cables such as Pata Parallel, SATA serial, ATA USB or SAS serial attached SCSI cables.
SCSI pronounces Scusi and sometimes colloquially known as Scuzzy. The small computer system interface let’s look into the improvements of HDD characteristics over time. Let’s look into how they all started in 1956 and how it has been developed to 2017. So the parameters follow capacity when formatted.
It started with 3.75 MB and entered in 14 TB physical volume. 68 Cubic feet, 1.9 cubic meter, now which is just 2.1 cubic inches, that is 34 cubic centimetres. Wait, mm pumps around 910 KGs now. It is just 2 point, 2 ounces 62 grams average access time. Approximately 600 milliseconds. Now, it is just to point to 10 milliseconds read/ write depends on the lap price.
It was nine thousand two hundred US dollars per megabyte in 1961. Now, they just cost 0.32 US dollars per gigabyte by 2015. Data density two thousand bits per square inch. Now, which is one point three terabytes and inch in 2015. Average lifespan – two hundred hours. Mean time between failures back in 1956. Now they are 2.5 million hours mean time between failures in 2017.
In-depth Comparison Between SSD & HDD
Which is better? An SSD or a Hard Drive? It is sort of like asking which is better out of a motorcycle and a Semi-Truck. Because they are not that comparable. They are just different. Let’s start with performance when it comes to raw speed. SSDs are faster. I see many folks comparing the sequential speed of an SSD to the sequential speed of a hard drive? Well they are a kind of similar but the reality of it is unless you copy large files back and forth all day, this specification is pretty much meaningless. Seriously, it has nothing to do with the way that they will do that, you will perceive the performance in the real world.
SSDs are all about little data transactions that happen all the time. All over the place when you are running something like an operating system on them. You know an instant message comes through a program launches it needs to access a ton of little files, all over the place. These are the times when not having to physically move ahead across a disk allows an SSD to utterly destroy a hard drive in terms of performance in system responsiveness. Any modern SSD will be easily several times faster than any hard drive and sometimes much more than that. That’s great but what if you have lots of data to store and that’s your main concern.
It’s not like playing back video or music files or looking at your archive of pictures requires blazing fast performance. So, this is where hard drives still excel at the time of writing this article. 160 Dollar buys you either a 256 Gigabyte SSD or a 4 Terabyte. Yes, a 16 times larger hard drive for that kind of difference in price per gig. You could be built two hard drives based storage boxes and have one of them set up as on off-site backup with the money that you saved by not using an SSD based backup solution.
For mass storage of data, we are a long way away from hard drives being replaced by SSDs. But, what about reliability. Now this one is a little bit complicated, hard drives are pretty reliable these days, but as devices with moving parts. They will die eventually. The good news is – they usually give warning signs like if your hard drive is making clicking noises right now for example, first check to make sure it has not turned into a dolphin and replace it if it is still hard drive. But the bad news is that any kind of use will wear them out for SSDs.
Reading from them a lot, don’t wear them out very much. Especially if you keep them running cool. But, if you write to them heavily, you can kill a consumer-grade model relatively quickly. So, I guess It should be put in this way – in an environment, the shock is an everyday occurrence such as in a notebook or tablet, I would choose SSD every time.
In an environment, where that’s not the case, the reliability in me is a secondary factor. After I determine my performance and storage needs which leads us to the in-between solution. Hybrid Drives, these leverage the technology of Hard Drives and SSDs at the same time. But, that’s a topic that is covered in our other guide as well.
Where Does Data Store In Hard Disk Drives?
Parts Of Hard Drives
Just to illustrate a couple of form factors that are designed. This is an example of a two and a half-inch drive as we call it. Which would be used for example in a notebook computer. This is what is called a three and a half-inch form factor. A hard disk drive is so named because the hard of the matter is where the data is stored. Which is on these disks and the data is stored magnetically as ones and zeroes or as magnetic bits that are oriented north or south. It is read or written, as we say by very small transducers on heads.
So this little roughly triangular-shaped feature can be thought of as the size of a bit. When we write and this is the right pole, the flux is essentially focussed through that pole. The corresponding area on the media below it is magnetized. The head is out flying on a suspension at the end of an arm. This is an arm which is part of what we call the head stack assembly. The arms move back and forth across the stroke and read the various tracks that are laid out on the disk.
These tracks are so narrow that we fit about 3,00000 of them in an inch of radius. The arms, the HSA pivot is actuated in this case. And, this is kind of fun. Magnetically, as we know electricity and magnetism exist together and when a current is run through a wire. There is a corresponding orthogonal magnetic field. So, how we are using that?
Here is that – there is a coil which is it’s hidden under this magnet. Under this plate, there is a magnet and below the magnet is a coil, the driving force of the magnet of the current or conversely the magnetism forces. The back end of the coil to move in one direction or the other right here we see the motor that spins the media.
2. Recording Data
When the drive is powered off, the heads are resting on this ram. The arm swings off so that the heads are preserved and they are not touching the media. Or, anything if I want to write or I want to read in other words. If I want to record a picture or If I want to bring out a picture file, the arms swing out over the disc and the heads are flying over the tracks. As we call them, so it goes to a very specific radius and the drive will be given an address to go. Let’s pretend that was the radius, that was the track that contains the picture or part of the picture.
That is the file that we said, please show me this picture, the data is recorded in magnetic domains that are a very small surface area on the disc. The Transducer on the head senses for that domain, the direction of the magnetism and whether it is a 1 or a 0 and that’s a bit the head takes all of those bits and transmits that electrically up into the channel. It is reconstructed back into a data form that we recognize as an image. What we are looking at right now is the surface on the recording head that’s facing the media surface.
So, the disc is spinning under the head and there is an airflow or share between this air bearing surface. And the media surface these darker areas are in relief outward and the medium range is inward and these surfaces in relief are functioning in the way that we would think of wings or the features on a Jet that control the flow of air. Everything that we can see in this view is only to support what we call the transducer, out at what is the trailing edge of the head. And, it’s where the magnetic flux is read and written or where we control the flux back and forth between the head and the disc.
This is a very close view of the transducer and at the top, it’s not necessarily possible to see here. But, will show a picture in a minute is what we call the right Pole. It’s a very tiny dot in the middle of a triangle at that location and that’s where the pole that writes is visible. Down in the middle of this stripe, is what we call the read element and that is the location where the magnetic signals are sensed.
For the read function, so our magnification right now is 85,000 and our micron bar is 200 nanometers. When you think about it and you think about the size of the molecules, we realize that some of these layers that we are looking at are roughly a few atoms or a few molecules thick. That is particularly true of the read element. And, it’s just a tiny dot or silver when we look at it even at a hundred thousand X and it as several layers which again are atoms thick at most. Very simple in concept and an amazing amount of technology.
Hopefully, with this guide, all your questions related to HDD vs SSD such as What does a hard drive do, mechanical hard drive, hard drive sizes, external hard drive, hard drive sizes, external hard drive, types of hard disk, SSD vs HDD speed and hard drive essay are answered. But, still, if you are facing any questions regarding What Is HDD? Where Does Data Store In Hard Disk Drives? SSD vs HDD? do let us know in the comment box below.
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