Greetings to all blog readers. Many are interested in the question - how is it arranged HDD computer. Therefore, I decided to dedicate today's article to this.
A computer hard disk (HDD or hard drive) is needed to store information after the computer is turned off, unlike RAM () - which stores information until the power is turned off (until the computer is turned off).
The hard drive, by right, can be called a real work of art, only engineering. Yes Yes exactly. It's so complicated inside everything is arranged. On the this moment All over the world, a hard drive is the most popular device for storing information, it is on a par with such devices as: flash memory (flash drives), SSD. Many people have heard about the complexity of the hard disk device and wonder how so much information is placed in it, and therefore would like to know how a computer hard disk is arranged or what it consists of. Today there will be such an opportunity).
A hard drive is made up of five main parts. And the first of them - integrated circuit , which synchronizes the work of the disk with the computer and manages all processes.
The second part is the electric motor(spindle), causes the disk to rotate at a speed of approximately 7200 rpm, and the integrated circuit keeps the rotation speed constant.
And now the third one the most important part is the rocker, which can both write and read information. The end of the rocker is usually divided so that you can work with several discs at once. However, the rocker head never comes into contact with the discs. There is a gap between the surface of the disk and the head, the size of this gap is about five thousand times smaller than the thickness of a human hair!
But let's still see what happens if the gap disappears and the rocker head comes into contact with the surface of the rotating disk. We still remember from school that F = m * a (Newton's second law, in my opinion), from which it follows that an object with a small mass and huge acceleration becomes incredibly heavy. Given the huge speed of rotation of the disk itself, the weight of the rocker head becomes very, very noticeable. Naturally, disk damage is inevitable in this case. By the way, this is what happened to the disk, in which this gap disappeared for some reason:
The role of the friction force is also important, i.e. its practically total absence when the rocker begins to read information, while moving up to 60 times per second. But wait, where is the engine here that drives the rocker, and even at such a speed? In fact, it is not visible, because it is electromagnetic system working on the interaction of 2 forces of nature: electricity and magnetism. Such interaction allows accelerating the rocker to the speed of light, in the literal sense.
Fourth part- the hard drive itself, this is where information is written and read from, by the way, there may be several of them.
Well, the fifth, final part of the hard drive design is, of course, the case in which all other components are installed. The materials used are as follows: almost the entire body is made of plastic, but the top cover is always metal. The assembled housing is often referred to as a "containment zone". There is an opinion that there is no air inside the containment area, or rather, that there is a vacuum there. This opinion is based on the fact that at such high disk rotation speeds, even a speck of dust that gets inside can do a lot of bad things. And this is almost true, except that there is no vacuum there - but there is purified, dried air or neutral gas - nitrogen, for example. Although perhaps more early versions hard drives, instead of cleaning the air - it was simply pumped out.
We talked about components, i.e. what is a hard drive made of. Now let's talk about data storage.
How and in what form is data stored on a computer hard drive
Data is stored in narrow tracks on the disk surface. During production, more than 200,000 such tracks are applied to the disc. Each of the tracks is divided into sectors.
Track and sector maps allow you to determine where to write or where to read information. Again, all information about sectors and tracks is located in the memory of an integrated circuit, which, unlike other components of a hard drive, is not located inside the case, but outside and usually from below.
The surface of the disc itself is smooth and shiny, but this is only at first glance. On closer examination, the surface structure turns out to be more complex. The fact is that the disk is made of a metal alloy coated with a ferromagnetic layer. This layer does all the work. The ferromagnetic layer remembers all the information, how? Very simple. The rocker head magnetizes a microscopic area on the film (ferromagnetic layer), setting the magnetic moment of such a cell to one of the states: o or 1. Each such zero and one are called bits. Thus, any information recorded on a hard disk is, in fact, a certain sequence and a certain number of zeros and ones. For example, photograph good quality occupies about 29 million of these cells, and is scattered across 12 different sectors. Yes, it sounds impressive, but in reality - such a huge number of bits takes up a very small area on the surface of the disk. Each square centimeter of hard disk surface contains several tens of billions of bits.
How a hard drive works
We have just examined the hard drive device, each of its components separately. Now I propose to link everything into a certain system, thanks to which the principle itself will be clear work hard disk.
So, how a hard drive works next: when the hard drive is put into operation, it means either it is being written to, or information is being read from it, or from it, the electric motor (spindle) starts to gain momentum, and since the hard drives are fixed on the spindle itself, respectively, they are together with it also start to rotate. And until the speed of the disk(s) has reached the level that an air cushion is formed between the rocker head and the disk, the rocker is in a special "parking zone" to avoid damage. Here's what it looks like.
As soon as the speed reaches the desired level, the servo drive (electromagnetic motor) sets in motion the rocker, which is already positioned in the place where you want to write or read information. This just contributes integrated circuit, which controls all movements of the rocker.
There is a widespread opinion, a kind of myth, that at times when the disk is "idle", i.e. no read / write operations are performed with it temporarily, the hard drives inside stop spinning. This is really a myth, because in fact, hard drives inside the case are constantly spinning, even when the hard drive is in power-saving mode and nothing is being written to it.
Well, here we have examined with you the device of the computer hard disk in all details. Of course, within the framework of one article, it is impossible to tell about everything related to hard drives. For example, in this article it was not said about - this is a big topic, I decided to write a separate article about it.
Found interesting video, about how the hard drive works in different modes
Thank you all for your attention, if you have not yet subscribed to updates of this site - I highly recommend doing this so as not to miss interesting and useful materials. See you on the blog pages!
We, the users personal computer, we often encounter the abbreviation HDD. And the desire to find out what an HDD is, where it is and what it is for is justified.
HDD stands for "hard disk drive". Simply put, it's a hard drive. Gradually fading into the past, they are being replaced by SSDs, but they will occupy their niche in the HDD market for a long time to come.
Why is the drive "hard"
HDD in the computer as soon as they are not called. Hard drive, hard drive, hard drive, screw - just a small list of his names. Why all the same "hard disk drive"?
Unlike "floppy" disks (floppies), HDD data is written to hard platters, which, in turn, are covered with a layer of ferromagnetic material. They are called nothing more than "magnetic disks". A hard drive uses one or more platters on the same axis. Readers (heads) do not touch the surface of the plates during operation. This is explained simply: with the rapid rotation of the plates, a layer of oncoming air flow is formed. The distance between the reader and the work surface is very small - only a few nanometers, and the air layer, which excludes mechanical contact, ensures a long service life. If the plates do not rotate at the proper speed, then the heads are in the so-called "parking" zone - outside the boundaries of the plates.
A distinctive feature of the HDD in a computer is that the storage medium is combined with the drive, as well as with the necessary electronics unit in one housing.
HDD Main Features
Like any technical device, the hard drive has a number of characteristics, based on which, we can draw conclusions about its relevance.
- Capacity is one of the most significant quantities. Specifies the amount of data that the drive can store.
- Dimensions (form factor). The most common variations are 3.5 and 2.5 inches. Specifies the width of the device.
- The speed of rotation of the axis, spindle. The number of revolutions per minute. The parameter significantly affects the speed of access to data and directly on the speed of their transfer. The most common options: 4200, 5400, 7200, 10,000 rpm.
- The number of I/O operations per second. For modern disks, this number approaches 50 (with random access to data), with sequential access, respectively, higher - about 100.
- Power consumption is an important parameter for portable devices (we are talking about laptops / netbooks).
- Buffer size. Buffer - intermediate memory. Its purpose is to smooth out read/write speed differences. In modern HDDs, it is usually located in the range from 8 to 64 megabytes.
I hope we were able to figure out what an HDD is in a computer, and even expand our horizons a little in the world of computer hardware.
Many of you know that all the information on the computer, presented in the form of files and folders, is stored on the hard drive. But, what is a hard drive and what it is intended for, not many will correctly answer. It is very difficult for people who are far from programming to imagine how information can be stored on some kind of piece of iron. After all, this is not a box or a piece of paper on which this very information can be written down and hidden in a box. Yes, a hard drive is not a box with a letter.
A hard disk (HDD, HMDD-from the English hard (magnetic) disk drive) is a magnetic storage medium. In computer slang, it is called "Winchester". It is designed to store information in the form of photos, pictures, letters, books. various formats, music, movies, etc. Outwardly, this device does not look like a disk at all. Rather, it looks like a small rectangular iron box.
The internals of a hard drive are like an old turntable.
Inside this metal box, there are round aluminum or glass disc plates located on the same axis along which the reading head moves. Unlike a player, the hard disk head does not touch the surface of the platters during operation.
For convenience, the hard disk is divided into several sections. This division is conditional. This is done using operating system or special programs. The new sections are called logical drives. They are assigned the letters C, D, E or F. It is usually installed on the C drive, and the files and folders are stored on other drives so that your files and folders do not suffer if the system crashes.
Watch a video about what a hard drive is:
Key Features of Hard Drives
- Form Factor is the width of the hard drive in inches. Standard size for desktop computer 3.5 inches, and for laptops 2.5 inches;
- Interface- in modern computers used to connect to motherboard SATA different versions. SATA, SATA II, SATA III. Older computers use the IDE interface.
- Capacity- this is maximum amount information that a hard drive can store is measured in gigabytes;
- Spindle speed is the number of spindle revolutions per minute. The faster the disk spins, the better. For operating systems, you need to install drives of 7200 rpm and higher, and for file storage, you can install drives with a lower speed.
- MTBF is the mean time between failures as calculated by the manufacturer. The larger it is, the better;
- Random access time- this is the average value of the time required for the head to position on an arbitrary section of the plate. The value is not constant.
- impact resistance is the ability of a hard drive to withstand pressure changes and shocks.
- Noise level, which the disc emits during operation is measured in decibels. The smaller it is, the better.
Already there SSD drives(solid-state drive in simple translation- solid state drive) that have neither a spindle nor platters. This is a storage device based on memory chips.
SSD drives are perfectly quiet and have very good read and write speeds. But they are still very expensive and not very reliable, so they are installed only under operating systems, and hard drives are used to store files. IDE drives and SATA.
Good day to all, my dear friends and readers. One friend told me that when he was still working in a video salon, a granny of 70-80 years old came to him. She approached a friend and said that she needed "HADEDE". A friend, as it were, did not immediately understand and asked again, they say hadede? She repeated it again, but when she saw that her friend was not drinking, she took out a piece of paper and said that her grandson had told her to buy Khadede.
On that piece of paper it was written HDD 160 GB. Well a friend chuckled and said it was a computer hard drive and sent them to another store. But that is no longer surprising. How could a granddaughter even send his grandmother for a hard drive? Well, did it collapse from the oak tree?
But what am I getting at? Let me tell you all the same what an HDD is in a computer. Then you will definitely not have questions if you want to buy it for yourself.
HDD (Hard Disk Drive) is the hard drive of your computer. You can hear in conversations and alternative titles this device, for example, "Winchester", "Screw", "Hard", "Hard", etc. This device is needed to store your information, in addition, the operating system in which you work is installed on it. Those. Without a hard drive, you can't really do much with your computer.
The hard disk is a long-term source of memory and after a power outage, all information remains on it, in contrast to a fast random access memory. Therefore, you can always store your files, photos, music, etc. on it. But of course this is a device, so do not forget about for greater security.
Theory of the origin of the name "Winchester"
I already hear the question “Why is it called a hard drive? It's a firearm!" Indeed, what can a storage device and a gun have in common? The fact is that in 1973 the notorious IBM company released the hard drive model 3340, but for consonance it was simply called “30-30”, which meant two modules of 30 megabytes each.
Chief Kenneth Haughton found the 30-30 consonance in the famous rifle. The fact is that the cartridges for this rifle had the same marking 30-30, where the first digit meant the size of the caliber in inches (0.30 - 7.62 cm), and the second digit meant the weight of the gunpowder in grains (this is not a typo, but a measure of weight ), which was loaded with a cartridge (30 grains is approximately 1.94 grams).
For convenience, it was decided to use such a name as slang. True, this slang has not been used by Americans for a long time, but we have not yet gone out of use, although more often it can be heard in the abbreviated name "Screw".
Hard disk device
Outwardly, this thing looks like a small rectangular box, but inside it there are several magnetic disks on one spindle, which look something like a CD. And of course, there is a certain reading head, which runs along these magnetic plates, reading all the information. Well, of course there are other components, but I think that these are all details.
And this work is somewhat similar to the work of a record player, only the reader is without a needle and does not touch magnetic disks, although the distance between them is simply negligible.
Main characteristics of the hard drive
Volume
The size of your hard drive determines how much information you can store on it. Over time, the memory sizes on new hard drives increase, as there is a real need for this. If on my first computer the volume was 40 GB and it was enough for me, now I have 2000 GB on my computer and I have already scored half. Of course, part can be removed without tears).
But there is one trick. Manufacturers write the size, for example, 500 GB, but when you connect the hard drive to a computer, you will see a much smaller volume there, somewhere around 476 GB. And where did the extra 24 GB go? Yes, everything is very simple.
Manufacturers round up the sizes of values, they say 1 GB is 1000 MB, 1 MB is 1000 KB, etc. It turns out that they are selling you a disk with a capacity of 500 million bytes, and if you divide by 1000, and then another 1000, you get 500 GB.
But after all, in 1 GB, in fact, not 1000, but 1024 MB, just as in 1 MB, not 1000, but 1024 KB. As a result, it turns out that we divide 500 million by 1024, and then by 1024 and get our 476 GB with a penny. I have about 140 GB on a 2 terabyte disk. Not bad, right? In general, now you will know.
Rotational speed
The performance of a hard drive is also determined by the spindle speed. And the greater this speed, the greater the performance of the disk, but the more energy is required and the greater the likelihood of failure.
For laptops and external hard drives, 5400 rpm is most often used, since this is really more appropriate for these devices. The speed of information exchange is less, but the probability of failure is less.
On stationary computers, in most cases, hard drives are installed at a speed of 7200 rpm. Here it is really beneficial, since the stationary ones, as a rule, have more powerful equipment capable of operating at such a speed. Plus, the computer is constantly connected to the outlet, which means there will be no shortage of energy.
There are more revolutions, even 15000, but I will not consider them here.
Connection interface
And of course, hard drives are constantly being improved and even their connection connectors are changing. Let's see what connectors are.
IDE (ATA/PATA) is the so-called parallel interface with a possible data usage rate of up to 133 MB per second. But today this interface is outdated and rigid with such a connector is no longer produced.
SATA - Serial interface, already more modern, which has come to replace IDE. The standard currently has three different revisions with different speed data transfer: SATA 1 - up to 150 MB / s, SATA 2 - up to 300 MB / s, SATA 3, up to 600 MB / s.
USB - This standard applies to external portable hard drives, which are connected to the computer via USB and you can safely work. The advantage of such a device is that you can turn it off at any time without turning off the computer itself.
There are other interfaces, such as SCSI or SAS, but these are no longer mandatory standards for simple use.
Form Factor
I was recently asked here, what is the form factor of hard drives? Everything is simple here. These are just its dimensions. There are 2.5 and 3.5 inches. Of course, there are others, but no one uses them in everyday life or they are outdated for a long time.
2.5" HDD is inserted into laptops, and 3.5" into stationary computers. I don't think you're confusing anything)
Well, that seems to be all that I wanted to tell you in this article. But I already hear: “Why didn’t you tell me about the SSD?”. My friends, you need to write a separate article about SSD, especially since this type is a high-speed solid-state drive. In general, I will definitely write about him).
Sincerely, Dmitry Kostin.
Today we will talk about what is HDD drives what they are, consider their characteristics. We will find out which of them are the best, and which HDDs are not worth buying.
A hard drive is an information storage device that is used in computers and laptops to install an operating system, drivers, programs on it, as well as to store all kinds of user files.
HDD - half mechanical, half electronic device, consisting of magnetic plates, reading heads, spindle (motor), and control board. The spindle, on which the magnetic plates are fixed, spins them up to several thousand revolutions. per minute. 
It is believed that the higher the torque of the spindle, then the speed of its reading is greater. Although to important factors include: random access time and recording density. HDD differ among themselves in speed, volume, and of course reliability. This parameter is guaranteed by the manufacturer.
What are the best manufacturing companies?
Samsung drives are considered the most reliable and fastest. Hitachi also produces very good rims but they are slower. HDD firms have average quality western digital. It turned out that this company initially began to produce its products at cheap factories that did not have high-quality equipment. by the most poor quality The production of devices of this type from well-known brands is the once leading American electronics company Seagate. Well, Fujitsu and Toshiba now cannot boast of the quality of hard disk production at all.
Therefore, when choosing a purchase HDD is better choose either Samsung or Hitachi. They differ in their dimensions. HDDs with a disk width of 3.5 (inches) are installed on computers, and 2.5 (inches) on laptops. 
Hard drive speed system block computer is more than 7000 rpm, but HDDs with a performance of no higher than 5500 rpm come across for sale. Such low-speed copies are not worth buying. But laptop drives with a rotation speed of 5400 rpm. They are much quieter and don't get as hot.
Buffer hard drive called cache memory, and serves to speed it up. It ranges from 32 to 128 MB. Although 32 MB. will be enough for its normal operation. The read and write speed is one of the most important parameters, which greatly affects the working performance of the device.
Information exchange rate
A good indicator for HDD is considered to be a read speed of 110 - 140 MB / s. You should not buy an HDD with a speed not exceeding 100 Mb / s. Random access time is second important indicator hard drive performance after reading and writing. It is believed that the smaller this parameter, the better the quality of the device. It mainly affects copying and reading small files. Pretty good if the HDD access time is 13 - 14 ms. carriers of this type come with two types of connectors. These are SATA 2 (earlier) and SATA 3. These connectors are compatible with each other, so this does not affect the operation of drives and their speed in any way. Over the last ten years hard drives haven't changed at all. Therefore, the price for them remained approximately at the same level.