The computer's hard drive is. Hard drive, what is it? What does a hard drive consist of and how does it work?

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 disks They were called “Winchesters” as a joke, but soon the name firmly stuck to them and became almost official.

How does a computer's hard drive work?

Principle hard devices computer disk remains 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.

An 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.

Upper layer hard drive serves for recording and reading 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 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 vibrations electric current, is supplied to the block of magnetic heads of the hard drive.


The heads find the desired section of the disk and convert current fluctuations into oscillations magnetic field. In this case, microscopic areas are created on the surface of the disk: some are magnetized, others are not magnetized. Binary code The recordings are 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 reminiscent of erasing information from a blackboard. 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 Latin letter. Size of each logical drive 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.

Computer hard drive is a place for long-term storage of information. In the computer specifications it is designated as HDD (Hard Disk Drive). In computer slang it is called a “hard drive” or “screw”. You can also hear the name “hard”. It received the name “Winchester” by analogy with the popular Winchester carbine, which used the “30-30 Winchester” cartridge. First HDD For personal computer was laid out into 30 tracks, each of which had 30 sectors, hence the name “hard drive”. A hard drive is a non-volatile component in a computer, i.e. When the power is turned off, the recorded (saved) data is not erased.

Hard drive device.

Data is stored on one or more aluminum or glass circular plates (disks) coated with a magnetic layer. The disk(s) are on a spindle and rotate at high speed, and a block of movable magnetic heads reads or writes data to the surface of the platters.

The disk(s) with the head unit are enclosed in a metal case to protect them from dust and mechanical influences. On the body there is electronic board, which controls the operation of the hard drive - the so-called controller. This entire device represents single block, which is located in a specially designated place “” and connected to motherboard special cable.

Basic characteristics of the hard drive.

Let's look at the main characteristics of hard disk you need to know.

VolumeHDD. Probably the most important characteristic, which determines the maximum possible volume for storing information. Denoted in gigabytes (GB) and terabytes (TB). Modern hard drives have capacities from 320 GB to 4 TB.

How can a novice user decide how much HDD capacity he needs? When choosing a computer, you should base your needs on it. If only for office use (text typing, printing, Internet, photo storage and processing...), then a hard drive with a capacity of 320-500 GB is sufficient. For games, watching movies, listening to music, you need a larger volume - from 500 GB to the maximum. A Blu-Ray movie can take up to 45 GB, and modern games are becoming more power-hungry, for example GTA 5 requires 65 GB of disk space.

Rotational speed. Another important characteristic that affects the performance of a hard drive. The faster the plates rotate, the faster access and recording data on them. The rotation speed is measured in revolutions per minute (rpm or rpm from the English rotate per minute). For use in personal computers, hard drives with 5400 rpm and 7200 rpm are produced. Hard drives with a rotation speed of 7200 rpm are preferable, but they are more expensive and noisier than drives with 5400 rpm.

Cache size or cache memory. Hard cache disk - a special type of RAM ( buffer memory), which stores frequently used data. Due to the fact that data is taken from a high-speed electronic cache, and not from a relatively slow mechanical medium, HDD performance increases. The larger the cache size, the fewer disk accesses. The size of buffer memory is measured in megabytes and in modern hard drives it is 16-128 MB.

All of the above characteristics are indicated in the price lists of computers in the store, and now you can easily navigate your choice.

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We, personal computer users, often come across the abbreviation HDD. And the desire to know what a HDD is, where it is and what it is needed for is justified.

HDD stands for " hard disk drive". Simply put, it is a hard drive. They are gradually becoming a thing of the past, being replaced by SSDs, but HDDs will occupy their niche in the market for a long time.

Why is the drive "hard"

There is no name for HDD in a computer. Hard drive, hard drive, hard drive, screw - just a small list of its names. Why "hard disk drive"?

Unlike “floppy” disks (floppy disks), data on HDDs is recorded on hard plates, and they, 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 one axis. Reading devices (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 incoming air flow is formed. The distance between the reading device and the working surface is very small - only a few nanometers, and the air layer, which eliminates 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 property of a HDD in a computer is that the storage medium is combined with a drive, as well as with a block of necessary electronics in one housing.

Main characteristics of HDD

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. Characterizes the amount of data that can be stored by the drive.
• Dimensions (form factor). The most common variations are 3.5 and 2.5 inches. Defines the width of the device.
• Rotation speed of the axis and spindle. The number of its revolutions per minute. The parameter significantly affects the speed of data access and directly 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, it is correspondingly higher - about 100.
• Energy consumption is an important parameter for portable devices(we're talking about laptops/netbooks).
• Buffer size. Buffer is intermediate memory. Its purpose is to smooth out differences in read/write speeds. In modern HDDs it is usually located in the range from 8 to 64 megabytes.

I hope we were able to understand what a HDD is in a computer, and even expand our horizons a little in the world of computer hardware.

Hello, friends! What is a hard drive or HDD? A hard drive is a hard magnetic disk drive. Abbreviated as HDD or hard (magnetic) disk drive - HDD or MHDD. The first hard drive was released by IBM in 1956 and had dimensions of about one cubic meter and was capable of storing up to 3.5 MB of information (see the picture on the left from Wikipedia). It consisted of 50 magnetic disks with a diameter of 610 mm. The surface of the disks was covered with pure iron, which made it possible to magnetize areas and store data. This hard drive weighs 971 kg and was part of the first production IBM 305 RAMAC computer. Further technology developed and reached what you see in your desktop PCs and laptops. A hard drive is also called a hard drive, a hard drive, or, for short, a screw. The name Winchester comes from the 70s. At that time, IBM released a new computer with a more modern hard drive, which consisted of two cabinets, each storing up to 30 MB of information. An analogy was drawn with the Winchester rifle, which used the 30-30 cartridge. Probably after this hard drives, most likely forever (by at least among the Russian-speaking population), the name stuck - Winchester or for short - screw.

A modern hard drive consists of:

• housing
• electronics unit
• actuator positioning unit
• block with magnetic plates

Let's look at each in more detail

Frame. It's like the body of a car. Everything rests on him. The main task is to provide the necessary rigidity and tightness. Rigidity is necessary to protect the disk from external damage. Tightness - to prevent foreign particles from entering the disk. The case is made of a heat-conducting alloy, since heat is generated during operation of the device and must be dissipated somehow. You can read more about HDD cooling. To equalize the pressures outside and inside the housing, a small window with a flexible metal plate is made.

Electronics unit

Comprises:

• interface block
• buffer or cache
• control unit

The interface unit is responsible for connecting the hard drive to the computer. ROM, a permanent storage device, records service information and disk firmware. Buffer is a cache memory similar to RAM. Frequently used information is placed in it, which increases the performance of the HDD. The cache read speed is approaching the maximum speed for the disk interface. On this moment the most common interface is SATA III with maximum throughput at 6 Gbit/s. The control unit is responsible for the functioning of the entire device. It monitors the rotation speed of the block with magnetic plates and the position of the block with actuators.

It consists of an actuator (a device for writing and reading information), a bracket (on which it all works) and a drive. The drive receives commands on where to read and where to write information from the control unit. (The picture below is taken from the site http://www.3dnews.ru/editorial/640707)

Block with memory plates. Consists of a drive, disks or plates and separators. The latter are used to set a certain distance between the plates. Discs with separators are mounted on the drive. The latter maintains a constant rotation speed.

2. How does a hard drive work?

When you turn on the computer, the control unit supplies power to the drive with magnetic disks and waits until the latter reaches the specified rotation speed. As soon as this happens, the computer receives a signal that the HDD is ready. Next comes the request for information. The positioning unit comes into play, which sets the desired position of the actuator. The data is read and goes into the interface block, and from there into the RAM.

Previously, actuators touched magnetic disks. As the speed of the latter increased, a different technology was required. In this case, the actuator hovered above the magnetic surface and touched the disk in a certain place. The technology has moved on, the rotation speeds of the plates have increased and the block with actuators began to be parked outside the plates. That is, the actuators are located next to the plates until the required speed rotation of magnetic disks.

Due to the high speed of rotation of the disks, an air flow is created that lifts the actuator head above the surface. The same air flow blows away dust particles trapped inside from the surface onto a special filter in the housing. There is also an adsorbent in the case to remove residual moisture.

In modern hard drives, the distance between the read head and the surface of the magnetic platinum< 10 нм. Благодаря тому, что считывающие головки никогда не касаются магнитных пластин отсутствует трение и продлевается срок жизни HDD.

Each magnetic plate is divided into ring tracks about 60 nm wide. The latter, in turn, are divided into clusters. Typically a cluster is 4 KB. Each bit of information represents a pad on a track that may be magnetized -1 or not -0. These sites are also called domains. How smaller size this site, so more information will fit on the track and a more capacious hard drive will be obtained. At the beginning of development, longitudinal recording was used. The site was located along the path. Later, this technology was replaced by perpendicular recording, which made it possible to increase data density and, in turn, increase HDD capacity.

The set of tracks equidistant from the center of rotation of the engine is called a cylinder.

Before hard drives exceeded the capacity limit of 500 MB, the CHS (cylinder-head-sector) positioning system was sufficient. With the growth in volume, the LBA (linear block addressing) positioning system was adopted in 1994. In the case of CHS, the hard drive was transparent to operating systems, but with linear addressing, the system addresses the desired hard sector disk, but already a block HDD management understands where this sector is physically located.

Actuator positioning unit. Driven by a solenoid motor. The latter consists of a stator and a coil. The stator consists of one or two permanent, strong neodymium magnets. Precise positioning of the bracket with the heads occurs by applying a voltage of a certain force to the coil (picture taken from http://www.3dnews.ru/editorial/640707)

The speed of head positioning and, consequently, the time of access to information depends on the strength of the magnets. The latter in hard drives varies from 3 to 12 ms. The shorter the time, the faster and more expensive the hard drive. WD has three series of hard drives: green, blue and black. The green one uses one neodymium magnet and a spindle speed of 5400 rpm. This results in rather modest performance, but decent efficiency and low power consumption. Blue discs use the same magnet and the rotation speed rises to 7200 rpm. In terms of speed characteristics, it occupies an intermediate position between green and black HDDs. Black ones use two magnets and a speed of 7200 rpm. This allows you to achieve maximum performance. You can increase the performance even higher by increasing the rotation speed of the motor with magnetic plates to 10,000 or 15,000 rpm. These discs have minimum time access to information and are mainly used in servers. Solid State Drives with Access Speed< 1 мс пока остаются вне конкуренции.

Hard drives produce two types of noise when operating. From rapidly rotating magnetic disks and from the impact of the block with heads on the limiter. The latter occurs when the block with heads returns to the parking position. To reduce this impact, manufacturers install rubber linings, but sometimes this does not help, especially on fast wheels. There are two ways to reduce noise from HDD. The first is to make shock-absorbing mounts in the PC case. You can read more about this. The second way is to use AAM technology, which I wrote about in more detail.

3. Hard drive production and manufacturers

In the beginning there were about 70 HDD manufacturers. Thanks to competition, there are only three left. These are Toshiba, Seagate and WD. In the diagram below you can see in which years the acquisitions took place

Production. In the machine shop, blanks are cut from cylindrical aluminum blanks. Then the workpieces are given required form perhaps even on lathes. After the workpiece is delivered to the polishing shop where the surfaces are polished to the required level. Then control takes place and the workpieces are sent to the magnetic coating workshop. Then control occurs again. Then the hard drive is assembled and low-level formatted. In this process, magnetic plates are divided into tracks and checked for broken or unreadable sectors. The latter are immediately marked to prevent the recording of information in them. Each track has a certain reserve of sectors. It is from this reserve that faulty areas discovered during operation are replaced.

Separately, it is necessary to say about the production of heads for reading and writing information. In modern hard drives, each actuator consists of two heads, one for reading and one for writing. The complexity of producing heads is comparable to the complexity of producing processors; photolithography is also used. The design of the heads is a production secret.

Conclusion

In the article we touched on a little history by providing a picture of the first hard drive released in 1956. They said possible reason naming magnetic hard disk drives in a short word - screw. Then we looked at the composition of the hard drive, what is hidden inside its case. We tried to pay attention to each block separately. Considered work hard disk. In the end, we figured out the manufacturers and the HDD production itself. I hope you have progressed with me in the HDD topic.