In detail and simply about the hard drive, also known as HDD (hard disk drive). Hard drive, what is it? What does a hard drive consist of and how does it work? Pros and cons of HDD versus SSD

Greetings to all blog readers. Many people are interested in the question of how a computer hard drive works. Therefore, I decided to devote today’s article to this.

A computer's hard drive (HDD or hard drive) is needed to store information after the computer is turned off, in contrast to RAM () - which stores information until the power supply is cut off (until the computer is turned off).

A hard drive can rightfully be called a real work of art, only an engineering one. Yes, yes, that's right. Everything inside is so complicated. At the moment, all over the world, the hard drive is the most popular device for storing information, it is on a par with devices such as flash memory (flash drives), SSD. Many people have heard about the complexity of the hard drive and are perplexed as to how it fits so much information, and therefore would like to know how the computer hard drive is structured or what it consists of. Today there will be such an opportunity).

A hard drive consists of five main parts. And the first of them is integrated circuit, which synchronizes 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 maintains the rotation speed constant.

And now the third, probably the most important part is the rocker arm, which can both write and read information. The end of the rocker arm is usually split to allow multiple discs to be operated at once. However, the rocker head never makes contact with the discs. There is a gap between the surface of the disc and the head, the size of this gap is approximately 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 a huge acceleration becomes incredibly heavy. Considering the enormous rotation speed 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 friction force is also important, i.e. its almost complete absence, when the rocker begins to read information, while moving up to 60 times per second. But wait, where is the engine that drives the rocker arm, and at such a speed? In fact, it is not visible, because it is an electromagnetic system that works on the interaction of 2 forces of nature: electricity and magnetism. This interaction allows you to accelerate the rocker to the speed of light, in the literal sense.

Part four- the hard drive itself is where information is written and read from; by the way, there can be several of them.

Well, the fifth and final part of the hard drive design is, of course, the case into 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 called a “hermetic zone”. There is an opinion that there is no air inside the containment zone, or rather, that there is a vacuum there. This opinion is based on the fact that at such high speeds of rotation of the disk, 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 in earlier versions of hard drives, instead of purifying the air, it was simply pumped out.

We were talking about components, i.e. what does a hard drive consist of?. Now let's talk about data storage.

How and in what form is data stored on a computer’s hard drive?

Data is stored in narrow tracks on the surface of the disk. During production, more than 200 thousand of these tracks are applied to the disc. Each track is divided into sectors.

Maps of tracks and sectors allow you to determine where to write or read information. Again, all information about sectors and tracks is located in the memory of the integrated circuit, which, unlike other components of the hard drive, is located not inside the case, but outside and usually at the bottom.

The surface of the disk itself is smooth and shiny, but this is only at first glance. Upon closer inspection, 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 drive, in fact, represents a certain sequence and a certain number of zeros and ones. For example, a good quality photograph 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 a hard drive's surface contains several tens of billions of bits.

How a hard drive works

We have just looked at the hard drive device, each of its components separately. Now I propose to connect everything into a certain system, thanks to which the very principle of operation of the hard drive will be clear.

So, the principle on which a hard drive works next: when the hard drive is put into operation, this means that either writing is being done to it, or information is being read from it, or from it, the electric motor (spindle) begins to gain momentum, and since the hard drives are attached to the spindle itself, accordingly they go with it also begin to rotate. And until the revolutions of the disc(s) have reached a level such that an air cushion is formed between the rocker head and the disc, the rocker arm is located in a special “parking zone” to avoid damage. This is what it looks like.

As soon as the revolutions reach the desired level, the servo drive (electromagnetic motor) moves the rocker arm, which is already positioned in the place where information needs to be written or read from. This is precisely facilitated by an integrated circuit that 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 temporarily performed with it, and the hard drives inside stop rotating. This is truly a myth, because in fact, the hard drives inside the case rotate constantly, even when the hard drive is in power-saving mode and nothing is written to it.

Well, we have looked at the device of a computer hard drive in detail. Of course, within the framework of one article, it is impossible to talk about everything related to hard drives. For example, this article did not talk about - this is a big topic, I decided to write a separate article about it.

I found an interesting video about how a hard drive works in different modes

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HDD is a data storage device - a hard magnetic disk drive. “HDD” is an abbreviation for the English phrase Hard Disk Drive. Other names for HDD: hard drive, hard drive, HDD, screw, hard, tin, tin.

What is HDD for?

HDD is used to store information. The information located on the hard drive is called data. The data on the disk is organized through a file system and is represented by files.

HDD is computer memory. Don't confuse it with RAM. The hard drive is non-volatile memory, RAM is volatile.

The hard drive is now the main information storage device, and if you have a computer, then you also have a screw.

Operating principle of HDD

Hard drives, that is, HDDs, work similarly to a device that everyone has long forgotten about - a “player”, with a rotating disk and a needle for playing music. The conversion elements (read/write heads) used in hard drives are similar to the read/write heads that are used in VCRs and stereo cassette recorders to access information on magnetic media.

Hard drives store information on a rotating metal or glass plate coated with magnetic material. As a rule, the disk consists of several plates connected by a common rod - a spindle. Each plate is something like a vinyl record with a recording that is played by a turntable. Information is usually stored on both sides of the plate.

As the disk spins, an element called the head reads or writes binary data onto the magnetic media. Information is written to the disk using some encoding method, of which there are a great many. The encoding method and recording density are determined by the disk controller.

Without delving further into the description of the operating principle of an HDD, we can say that a hard drive is, in fact, a super player with a bunch (or maybe just one) of gramophone records inside. Although, of course, in terms of the complexity of the device, the player was not lying around with it.

The past and future of HDD

The very first HDD was developed by IBM in the early 70s.

In 1983, with the release of the first IBM PC/XT computer, a hard drive from Seagate Technology appeared in the lives of thousands of newly minted, still wild users. The early hard drive interface, developed by Alan Shugart (founder of Seagate Technology), was the de facto standard for HDDs for many years. Subsequent developments by Seagate formed the basis for the ESDI and IDE interfaces. Shugart also developed the SCSI interface, which is now used in many modern computers.

By the way, Seagate hard drives are now the best-selling in Europe. And who in Russia doesn’t know the famous Barracudas?

The most important direction in the development of hard drive technology has always been to increase their (storage) capacity. Progress in this area is particularly driven by ever-increasing software requirements. Increasing the capacity of drives is possible either by increasing the size of the drives themselves or by increasing the data storage density. The limit for increasing HDD sizes has been reached, the limit for data storage density has not yet been reached. But it won't be long.

Need to know

1. HDD is a complex contraption for storing information

2. The hard drive is short-lived and is unlikely to last more than three years with constant use.

3. It is extremely undesirable to carry a hard drive (somewhere), twirl it in your hands, or even remove it from the computer case. Winchester is very sensitive to vibration!

4. The internal structure of the HDD is very complex. If you once went to a circle of young radio amateurs, this does not mean at all that you can now repair hard drives. Repairing hard drives requires more than just a soldering iron!

5. Those who like to tinker with hardware need to remember that by opening the HDA of the disk, you thereby put an end to both the information and the hard drive itself

6. In terms of storage security, storage media can be arranged in this order (with an increasing risk of data loss): head, paper, hard drive. Do not store important information on the HDD! And if you have to, always make backups!

7. If the information on your hard drive is unavailable for some reason, do not try to restore it! Most likely, you will only completely destroy it - it is better to turn to professionals. Data recovery is no big deal!

8. The word “HDD” is a dirty word and is not used in polite society; it characterizes something (to put it mildly) unreliable, short-lived and disgusting

Currently, the hard disk drive is the most popular electronic data storage device. It is used both in our regular computers and laptops, and in servers.
Many of you have probably heard a different name for a hard drive. For example, HDD, screw or screw. And if the first abbreviation comes from the completely understandable hard disk drive, then other expressions mean nothing to most. So, these abbreviations come from another slang name for a hard drive - “hard drive”. If you would be interested in finding out where this expression came from and who its author is, then read the article further.

The history of the second name of the hard drive

For most people, a hard drive means a type of firearm, but not a computer device. So why is a hard drive called a “Winchester” and where did it come from?

Historically, it was created by engineers of the IBM corporation and it also received the name hard drive from them. In 1973, when IBM developed a new drive model, the IBM-3340, engineers used its internal short working name “30-30” for ease of communication. This name reflected the internal structure of the disk. It consisted of two packages of disks in a maximum configuration of 30 megabytes each. The 3340 hard drive model was the first to use read/write heads, which, due to aerodynamic forces arising from the speed of rotation of the drives, hovered above the surface, which significantly reduced the air gap between the head and the drive. Also, the disk platters and read heads were combined in one non-separable sealed housing, which eliminated any external influence and increased the reliability of the device. Well, the name “Winchester” (from the English Winchester) was given to the drive thanks to the project manager, Kenneth Houghton, who, during a routine discussion of what to call the hard drive, accidentally called it a hard drive.

This name turned out to be consonant with the very popular at that time hunting weapon Winchester Model 1894 using a cartridge marked .30-30 Winchester, which meant the caliber size in hundredths of an inch “.30” or 7.62 mm and the weight of gunpowder in grains “30” or 1.94 grams.

According to another version, the hard drive received this name only because of the cartridges themselves and the weapon had nothing to do with it.

Conclusion

One way or another, the second name for a hard drive – hard drive – has gone down in history and is still in common use, although sometimes it is shortened to the words “screw” or “vinch”. In Europe and the USA, the name “Winchester” fell out of use back in the 1990s, but in the Russian language it was preserved and received semi-official status.

Most likely, with the massive arrival of solid-state drives, hard drives will no longer be called that and this slang name will become a thing of the past in our country, but this will not happen soon.

Hard drive(HDD, SCREW, WINCHESTER) is an information storage device in a personal computer. Hard drive – designed for storing and transmitting information. A hard drive stores data on the magnetic surface of the disk. Information is recorded and retrieved using magnetic heads. A hard drive can contain several platters called disks. The motor that rotates the disk turns on when power is applied to the disk and remains turned on until the power is removed. The motor rotates at a constant speed, measured in revolutions per minute (rpm). Data is organized on a disk in cylinders, tracks, and sectors. Cylinders are concentric tracks on disks, located one above the other. The track is then divided into sectors. The disk has a magnetic layer on each side. Each pair of heads is mounted, as it were, on a “fork” that clasps each disk. This “fork” moves above the surface of the disk using a separate servo motor (and not a stepper, as is often mistakenly thought - a stepper motor does not allow you to move quickly above the surface). All hard drives have spare sectors that are used by its management circuitry if bad sectors are detected on the drive.

Hard drive device:

Hard drive interfaces

A storage interface is a set of electronics that ensures the exchange of information between the device controller (cache buffer) and the computer. An interface is the way the hard drive and computer motherboard interact. It is a set of special lines and a special protocol (a set of data transfer rules). That is, purely physically, it is a cable (cable, wire), on both sides of which there are inputs, and on the hard drive and motherboard there are special ports (places where the cable is connected). Thus, the concept of interface includes a connecting cable and ports located on the devices it connects.

IDE- translated from English “Integrated Drive Electronics”, which literally means “built-in controller”. It was only later that IDE began to be called an interface for data transfer, since the controller (located in the device, usually in hard drives and optical drives) and the motherboard had to be connected with something. It (IDE) is also called ATA (Advanced Technology Attachment), it turns out something like “Advanced Connection Technology”.

What can I say, although the IDE was very slow (the data transfer bandwidth ranged from 100 to 133 megabytes per second in different versions of the IDE - and even then purely theoretically, in practice it was much less), but it allowed you to simultaneously connect two devices to the motherboard at once , using one loop.

Moreover, in the case of connecting two devices at once, the line capacity was divided in half. However, this is far from the only drawback of the IDE. The wire itself, as can be seen from the figure, is quite wide and, when connected, will take up the lion's share of the free space in the system unit, which will negatively affect the cooling of the entire system as a whole. All in all IDE is already outdated morally and physically, for this reason the IDE connector is no longer found on many modern motherboards, although until recently they were still installed (in the amount of 1 piece) on budget motherboards and on some boards in the mid-price segment.

The next interface, no less popular than the IDE in its time, is SATA (Serial ATA), a characteristic feature of which is serial data transmission. It is worth noting that at the time of writing this article, it is the most widespread for use in PCs.

Interfaces SATA, SATA 2(II), SATA 3 (III)

In 2002, the first hard drives appeared, with a progressive interface at that time SATA . The maximum data transfer speed of which was 150 MB/s.

If we talk about the advantages, the first thing that catches your eye is the replacement 80-wire loop (Fig. 1), to a seven-core SATA cable (Fig. 3), which is much more resistant to interference, which made it possible to increase the standard cable length from 46 cm to 1 m. Also, corresponding SATA connectors have been developed (Fig. 4), which are several times more compact than the connectors of the previous IDE standard. This made it possible to place more connectors on the motherboard; now on new motherboards you can find more than 6 SATA connectors, versus the traditional 2-3 IDE in older motherboards oriented to this standard.

Then, the SATA II standard appeared, the data transfer speed reached 300 MB/s. This standard has many advantages, including: Native Command Queuing technology (it was this technology that made it possible to achieve a speed of 300 MB/s), hot-plugging disks, executing several commands in one transaction, and others.

Well, in 2009 the interface was introduced SATA 3 . This standard provides for data transfer at speeds 600 MB/s (for hard drives, “oh” how redundant).

Interface improvements can include more efficient power management and, of course, increased speed.

It should be noted that SATA, SATA II and SATA III are completely compatible.

1956 - IBM 350 hard drive as part of the first production computer, the IBM 305 RAMAC. The drive occupied a box the size of a large refrigerator and weighed 971 kg, and the total memory capacity of 50 thin disks covered with pure iron with a diameter of 610 mm rotating in it was about 5 million 6-bit bytes.
1980 - the first 5.25-inch Winchester, Shugart ST-506, 5 MB.
1981 - 5.25-inch Shugart ST-412, 10 MB.
1986 - SCSI, ATA standards.
1990 - maximum capacity 320 MB.
1995 - maximum capacity 2 GB.
1997 - maximum capacity 10 GB.
1998 - UDMA/33 and ATAPI standards.
1999 - IBM releases Microdrive with capacities of 170 and 340 MB.
2000 - IBM releases Microdrive with capacities of 500 MB and 1 GB.
2002 - ATA/ATAPI-6 standard and drives with a capacity of over 137 GB.
2003 - the appearance of SATA.
2003 - Hitachi releases Microdrive with a capacity of 2 GB.
2004 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 2.5 and 5 GB.
2005 - maximum capacity 500 GB.
2005 - Serial ATA 3G standard.
2005 - SAS appeared.
2005 - Seagate releases ST1 - an analogue of the Microdrive with a capacity of 8 GB.
2006 - application of the perpendicular recording method in commercial drives.
2006 - the appearance of the first “hybrid” hard drives containing a flash memory unit.
2006 - Seagate releases ST1 - an analogue of the Microdrive with a capacity of 12 GB.
2007 - Hitachi introduces the first commercial drive with a capacity of 1 TB.
2009 - based on Western Digital 500 GB platters, then Seagate Technology LLC released models with a capacity of 2 TB.
2009 - Samsung released the first hard drives with USB 2.0 interface
2009 - Western Digital announced the creation of 2.5-inch HDDs with a capacity of 1 TB
2009 - the emergence of the SATA 3.0 standard.
2010 - Seagate releases a 3 TB hard drive.
2010 - Samsung releases a hard drive with platters with a recording density of 667 GB on one platter
2011 - Western Digital released the first disk on 750 GB platters.

One of the main components of any computer is a hard magnetic disk, which is used as a storage device for permanent information.

This device has several “informal” names: hard disk, hard drive or “screw”.

Why is a hard drive called a hard drive?

Computer hard drives began to be called Winchesters in the United States in the 70s of the twentieth century. Then IBM released the first analogue of modern hard drives: a device consisting of two cabinets, inside of which there were magnetic disks with a capacity of 30 MB each.

It was marked with the inscription “30x30” - exactly the same inscription was present on the rifle of the famous company “Winchester”. At first, hard drives were called “hard drives” as a joke, but soon the name firmly stuck to them and became almost official.

How does a computer's hard drive work?

The principle of a computer hard drive has remained unchanged for several decades. Of course, the technical details have undergone major changes, but the main features of the design remain the same as forty years ago.

The hard drive consists of several thin glass or aluminum disks, on the surface of which a thin layer of chromium dioxide is applied. The disks are fixed strictly parallel to each other on the spindle and covered with an aluminum housing. In addition, there is a block of magnetic heads inside the case.

The electric motor drives the discs and they begin to rotate at a constant speed. The resulting air flows keep the heads at a certain distance from the surface of the disks, so that there are no scratches or abrasions on it.

The top layer of the hard drive is used to write and read information. This work is performed by magnetic heads that move over the surface of the disks, finding the desired positions using special marks on the disk.

Of course, the diameters of modern hard drives have decreased significantly compared to the first models, and the information capacity, on the contrary, has increased hundreds of thousands of times. However, the first hard drives had approximately the same basic design.

Writing information to the hard drive

The process of writing and reading information is based on a binary code: the presence or absence of a signal. The information block encrypted in this way, converted into oscillations of electric current, is supplied to the block of magnetic heads of the hard drive.

The heads find the desired area of the disk and convert current fluctuations into magnetic field fluctuations. In this case, microscopic areas are created on the surface of the disk: some are magnetized, others are not magnetized. The binary recording code is thus transferred to the hard drive.

The process of reading information looks similar: a block of magnetic heads passes over the desired area of the disk, and due to the presence of oscillations in the magnetic field generated by the surface of the disk, the electrical voltage in the heads either increases or decreases.

The read information goes to where it is processed and displayed on the screen. The monitor shows us text or an image that is stored on the hard drive.

Formatting your hard drive

The process of formatting a hard drive is similar to erasing information from a school board. Magnetic heads completely destroy everything that was previously written on the disk and break its surface into sectors for new recordings. Brand new disks are also formatted: this is necessary to streamline the writing and reading process.

Presentation of information on the hard drive

Information is written to the hard drive not randomly, but in the form of circles (tracks) located one inside the other. The hard drive consists of several disks, and each head is responsible for one side of one disk, but they all move simultaneously to the same depth.

Therefore, information is recorded on several disks at once, the tracks of which form a cylindrical surface. Disks are divided into sectors, with one sector track containing 512 bytes.

The logical presentation of information is different from its physical layout. During formatting, the hard drive is divided into so-called logical drives, each of which is designated by a Latin letter. The size of each logical drive is assigned arbitrarily, at the request of the computer owner.

This presentation of information has been chosen for the convenience of users. To convert logical coordinates into physical ones, there is a special translator located in the hard drive case.