The structure and principle of operation of a hard drive. Hard disk (magnetic drive, hard drive, HDD)

If we consider the hard drive as a whole, it consists of two main parts: this is the electronics board on which the “brain” of the hard drive is located, so to speak. It contains a processor, a control program, a random access memory, and a recording and reading amplifier. The mechanical part includes such parts as a block of magnetic heads with the abbreviation BMG, a motor that rotates the plates, and of course the plates themselves. Let's look at each part in more detail.

Hermetic block.

The hermetic block, also known as the hard drive enclosure, is designed for fastening all parts, and also serves as protection against dust particles getting onto the surface of the plates. It is worth noting that opening the HDA can only be done in a room specially prepared for this, in order to avoid dust and dirt getting inside the case.

Integrated circuit.

An integrated circuit or electronics board synchronizes the operation of the hard drive with the computer and controls all processes; in particular, it maintains a constant speed of rotation of the spindle and, accordingly, the platter, which is carried out by the motor.

Electric motor.

An electric motor or engine rotates the plates: about 7200 revolutions per second (an average value is taken, there are hard drives on which the speed is higher and reaches 15,000 revolutions per second, and there are also with a lower speed of about 5400, the speed of access to the plates depends on the speed of rotation of the plates necessary information on the hard drive).

Rocker.

The rocker is designed for writing and reading information from the hard drive plates. The end of the rocker arm is divided and there is a block of magnetic heads on it; this is done so that information can be written to and read from several plates.

Block of magnetic heads.

The rocker arm includes a block of magnetic heads, which quite often fails, but this “often” parameter is very conditional. Magnetic heads are located on top and bottom of the platters and are used to directly read information from the platters located on the hard drive.

Plates.

The plates directly store information; they are made of materials such as aluminum, glass and ceramics. Aluminum is the most widely used, but the other two materials are used to make so-called “elite wheels”. The first plates produced were coated with iron oxide, but this ferromagnet had a big drawback. Discs coated with such a substance had little wear resistance. On at the moment Most hard drive manufacturers coat the platters with chromium cobalt, which has an order of magnitude higher safety margin than iron oxide. The plates are attached to the spindle at the same distance from each other; this design is called a “package”. An engine or electric motor is located under the disks.

Each side of the plate is divided into tracks, they in turn are divided into sectors or otherwise blocks, all tracks of the same diameter represent a cylinder.

All modern hard drives have a so-called “engineering cylinder”; service information is stored on it, such as the hdd model, serial number etc. This information is intended to be read by a computer.

Principle work hard disk

The basic operating principles of a hard drive have changed little since its inception. The device of a hard drive is very similar to an ordinary record player. Only under the body there can be several plates mounted on a common axis, and the heads can read information from both sides of each plate at once. The rotation speed of the plates is constant and is one of the main characteristics. The head moves along the plate at a certain fixed distance from the surface. The smaller this distance, the greater the accuracy of information reading, and the greater the information recording density can be.

When you look at the hard drive, all you see is a durable metal casing. It is completely sealed and protects the drive from dust particles, which, if they get into the narrow gap between the head and the surface of the disk, can damage the sensitive magnetic layer and damage the disk. In addition, the case shields the drive from electromagnetic interference. Inside the case are all the mechanisms and some electronic components. The mechanisms are the disks themselves on which information is stored, the heads that write and read information from the disks, and the motors that set it all in motion.

The disk is a round plate with a very smooth surface, usually made of aluminum, less often of ceramics or glass, coated with a thin ferromagnetic layer. Many drives use an iron oxide layer (which coats regular magnetic tape), but latest models hard drives work with a layer of cobalt about ten microns thick. This coating is more durable and, in addition, allows you to significantly increase the recording density. The technology of its application is close to that used in the production of integrated circuits.

The number of disks can be different - from one to five, the number of working surfaces is correspondingly twice as large (two on each disk). The latter (as well as the material used for the magnetic coating) determines the capacity of the hard drive. Sometimes the outer surfaces of the outer disks (or one of them) are not used, which makes it possible to reduce the height of the drive, but at the same time the number of working surfaces is reduced and may turn out to be odd.

Magnetic heads read and write information to disks. The recording principle is generally similar to that used in a conventional tape recorder. Digital information is converted into variable electric current, arriving at the magnetic head and then transferred to the magnetic disk, but in the form magnetic field, which the disk can perceive and “remember”.

The magnetic coating of the disk consists of many tiny areas of spontaneous magnetization. To illustrate, imagine that the disk is covered with a layer of very small compass arrows pointing in different directions. Such arrow particles are called domains. Under the influence of an external magnetic field, the domains' own magnetic fields are oriented in accordance with its direction. After the termination of the external field, zones of residual magnetization are formed on the surface of the disk. In this way, the information recorded on the disk is saved. Areas of residual magnetization, when rotating the disk opposite the gap of the magnetic head, induce electromotive force, varying depending on the magnitude of magnetization.

The disk package, mounted on the spindle axis, is driven by a special motor compactly located underneath it. In order to reduce the time it takes for the drive to become operational, the engine runs in forced mode for some time when turned on. Therefore, the computer's power supply must have a reserve of peak power. Now about the operation of the heads. They move with the help of a stepper motor and seem to “float” at a distance of a fraction of a micron from the surface of the disk, without touching it. As a result of recording information, magnetized areas are formed on the surface of disks in the form of concentric circles.

They are called magnetic tracks. Moving, the heads stop over each next track. A set of tracks located one under the other on all surfaces is called a cylinder. All drive heads move simultaneously, accessing cylinders of the same name with the same numbers.

Hard drive ("hard drive", hdd, hard disc drive - eng.) - an information storage device based on magnetic plates and the magnetism effect.

Applicable everywhere in personal computers, laptops, servers and so on.

Hard disk device. How does a hard drive work?

On the floor hermetically sealed the block contains double-sided plates, with magnetic layer, planted on motor shaft and rotating at speeds from 5400 rpm. The block is not completely sealed, but the most important thing is that it does not leak fine particles and does not allow humidity changes. All this has a detrimental effect on the service life and quality of the hard drive.

In modern hard drives, . This produces less noise during operation, significantly increases durability and reduces the chance of shaft jamming due to collapse.

Reading and writing is done using head block.

In working order, heads soar above the disk surface at a distance ~10nm. They are aerodynamic and rise above the surface of the disk due to updraft from the rotating plate. Magnetic heads can be located on both sides plates, if magnetic layers are deposited on each side of the magnetic disk.

The connected head block has fixed position, that is, the heads move all together.

All heads are controlled by a special drive based on electromagnetism.

Neodymium magnet creates magnetic field, in which the head unit can move with a high reaction speed under the influence of current. This is the best and fastest option for moving the head block, but once upon a time the head block was moved mechanically, using gears.

When the drive is turned off, to prevent the heads from falling onto the drive and damaged him, they're cleaning up head parking area(parking zone, parking zone).

This also allows you to transport switched off hard drives without any restrictions. When turned off, the disk can withstand heavy loads without being damaged. When turned on, even a small jolt at a certain angle can destroy the magnetic layer of the platter or damage the heads when touching the disk.

In addition to the sealed part, modern hard drives have an external control board. Once upon a time, all control boards were inserted into expansion slots on the computer motherboard. It was not convenient in terms of versatility and capabilities. Nowadays, with hard drives, all the electronics that control the drive and the interface are located on a small board at the bottom of the hard drive. Thanks to this, it is possible to configure each disk to certain parameters that are advantageous from the point of view of its structure, giving it a gain in speed, or quieter operation, for example.

To connect the interface and power, standard generally accepted connectors are used / and Molex/Power SATA.

Peculiarities.

Hard drives are the most capacious custodians of information and relatively reliable. Disk volumes are constantly growing, but lately this is due to some difficulties and to further expand the volume, new technologies are required. We can say that hard drives have almost reached a straight line in achieving maximum opportunities. The spread of hard drives was mainly driven by the ratio pricevolume. In most cases, a gigabyte of disk space costs less than 2.5 rubles.

Pros and cons of hard drives compared to .

Before the advent of solid state SSD(solid state drive) - drives; hard drives had no competitors. Now hard drives have a direction to aim for.

Disadvantages of hard drives(hard drive)(ssd) drives:

low sequential read speed
low access speed
low reading speed
slightly slower write speed
vibrations and slight noise during operation

Although, on the other hand, hard drives have other more significant the benefits to which SSD hoarders strive and strive.

Pros hard drives (hard drive) compared to solid state (ssd) drives:

significantly better volume price
the best indicator of reliability
larger maximum volume
in case of failure, there is a much greater chance of data recovery
the best option for use in media centers, due to its compactness and large capacity of 2.5 drives

About what worth paying attention when choosing a hard drive, you can look in our article ““. If you need hard repair disk or information recovery, you can refer to.

What does a modern hard drive (HDD) look like inside? How to take it apart? What are the parts called and what functions do they perform in the general information storage mechanism? Answers to these and other questions can be found here below. In addition, we will show the relationship between Russian and English terminologies describing the components of hard drives.

For clarity, let's look at the 3.5-inch SATA drive. This will be a completely new Seagate ST31000333AS terabyte. Let's examine our guinea pig.

The green plate secured with screws with a visible trace pattern, power and SATA connectors is called an electronics board or control board (Printed Circuit Board, PCB). It performs the functions of electronic control of the hard drive. Its work can be compared to putting digital data into magnetic fingerprints and recognizing it back on demand. For example, like a diligent scribe with texts on paper. The black aluminum case and its contents are called the Head and Disk Assembly (HDA). Among specialists, it is customary to call it a “can.” The case itself without contents is also called a hermetic block (base).

Now let's remove the printed circuit board (you'll need a T-6 star screwdriver) and examine the components placed on it.

The first thing that catches your eye is the large chip located in the middle - the System On Chip (SOC). There are two major components in it:

The central processor that performs all calculations (Central Processor Unit, CPU). The processor has input/output ports (IO ports) to control other components located on printed circuit board, and data transfer via the SATA interface.
Read/write channel – a device that converts incoming data from the heads analog signal into digital data during a read operation and encoding the digital data into an analog signal during a write operation. It also monitors the positioning of the heads. In other words, it creates magnetic images when writing and recognizes them when reading.

The memory chip is a regular DDR SDRAM memory. The amount of memory determines the size of the hard drive cache. This PCB has Samsung memory DDR with a capacity of 32 MB, which in theory gives the disk a cache of 32 MB (and this is exactly the volume given in technical characteristics ah hard drive), but this is not entirely true. The fact is that the memory is logically divided into buffer memory (cache) and firmware memory. The processor requires a certain amount of memory to load firmware modules. As far as we know, only the HGST manufacturer indicates the actual cache size in the technical specifications description; Regarding other disks, we can only guess about the actual cache size. In the ATA specification, the drafters did not expand the limit set in earlier versions, equal to 16 megabytes. Therefore, programs cannot display a volume greater than the maximum.

The next chip is a spindle motor and voice coil control controller that moves the head unit (Voice Coil Motor and Spindle Motor controller, VCM&SM controller). In the jargon of specialists, this is a “twist”. In addition, this chip controls secondary power supplies located on the board, which power the processor and the preamplifier-switch chip (preamplifier, preamp), located in the HDA. This is the main energy consumer on the printed circuit board. It controls the rotation of the spindle and the movement of the heads. Also, when the power is turned off, it switches the stopping engine to generation mode and supplies the resulting energy to the voice coil for smooth parking of the magnetic heads. The VCM controller core can operate even at temperatures of 100°C.

Part of the disk control program (firmware) is stored in flash memory (indicated in the figure: Flash). When power is applied to the disk, the microcontroller first loads a small boot ROM inside itself, and then rewrites the contents of the flash chip into memory and begins executing code from RAM. Without correctly loaded code, the disk will not even want to start the engine. If there is no flash chip on the board, it means it is built into the microcontroller. On modern drives (from about 2004 and newer, but the exception is Samsung hard drives and those with Seagate stickers), flash memory contains tables with mechanics and head settings codes that are unique to a given HDA and will not fit another. Therefore, the “switch controller” operation always ends either with the disk being “not detected in the BIOS” or determined by the factory internal name, but still does not provide access to data. For the considered Seagate drive 7200.11 the loss of the original contents of flash memory leads to a complete loss of access to information, since it will not be possible to select or guess the settings (in any case, such a technique is not known to the author).

On the R.Lab YouTube channel there are several examples of rearranging a board with re-soldering a microcircuit from a faulty board to a working one:
PC-3000 HDD Toshiba MK2555GSX PCB change
PC-3000 HDD Samsung HD103SJ PCB change

The shock sensor reacts to shaking that is dangerous for the disk and sends a signal about it to the VCM controller. The VCM immediately parks the heads and can stop the disk from spinning. In theory, this mechanism should protect the disc from further damage, but in practice it does not work, so do not drop the discs. Even if you fall, the spindle motor may jam, but more on that later. On some disks, the vibration sensor is highly sensitive, responding to the slightest mechanical vibrations. The data received from the sensor allows the VCM controller to correct the movement of the heads. In addition to the main one, such disks have two additional vibration sensors installed. On our board additional sensors not soldered, but there are places for them - indicated in the figure as “Vibration sensor”.

The board has another protective device - a transient voltage suppression (TVS). It protects the board from power surges. During a power surge, the TVS burns out, creating short circuit to the ground. This board has two TVS, 5 and 12 volts.

The electronics for older drives were less integrated, with each function divided into one or more chips.

Now let's look at the HDA.

Under the board there are contacts for the motor and heads. In addition, there is a small, almost invisible hole on the disk body (breath hole). It serves to equalize pressure. Many people believe that there is a vacuum inside the hard drive. Actually this is not true. Air is needed for the aerodynamic take-off of the heads above the surface. This hole allows the disc to equalize the pressure inside and outside the containment area. WITH inside this hole is covered with a filter (breath filter), which traps dust and moisture particles.

Now let's take a look inside the containment zone. Remove the disk cover.

The lid itself is nothing interesting. It's just a steel plate with a rubber gasket to keep out dust. Finally, let's look at the filling of the containment zone.

Information is stored on disks, also called "platters", magnetic surfaces or plates. Data is recorded on both sides. But sometimes on one side the head is not installed, or the head is physically present, but is disabled at the factory. In the photo you can see the top plate corresponding to the head with the highest number. The plates are made of polished aluminum or glass and are coated with several layers of different compositions, including a ferromagnetic substance on which the data is actually stored. Between the plates, as well as above the top of them, we see special inserts called dividers or separators. They are needed to equalize air flows and reduce acoustic noise. As a rule, they are made of aluminum or plastic. Aluminum separators cope more successfully with cooling the air inside the containment zone. Below is an example of a model for the passage of air flow inside a hermetic unit.

Side view of the plates and separators.

Read-write heads (heads) are installed at the ends of the brackets of the magnetic head unit, or HSA (Head Stack Assembly, HSA). The parking zone is the area where the heads of a healthy disk should be if the spindle is stopped. For this disk, the parking zone is located closer to the spindle, as can be seen in the photo.

On some drives, parking is carried out on special plastic parking areas located outside the plates.

Storage parking area Western Digital 3.5”

In the case of parking the heads inside the plates, a special tool is needed to remove the block of magnetic heads; without it, it is very difficult to remove the BMG without damage. For external parking, you can insert plastic tubes of suitable size between the heads and remove the block. Although, there are also pullers for this case, but they are of a simpler design.

The hard drive is a precision positioning mechanism, and for its normal operation very clean air is required. During use, microscopic particles of metal and grease can form inside the hard drive. To immediately clean the air inside the disc, there is a recirculation filter. This is a high-tech device that constantly collects and traps tiny particles. The filter is located in the path of air flows created by the rotation of the plates

Now let's remove the top magnet and see what's hidden underneath.

Hard drives use very powerful neodymium magnets. These magnets are so powerful that they can lift up to 1,300 times their own weight. So you should not put your finger between the magnet and metal or another magnet - the blow will be very sensitive. This photo shows the BMG limiters. Their task is to limit the movement of the heads, leaving them on the surface of the plates. BMG limiters different models are designed differently, but there are always two of them, they are used on all modern hard drives. On our drive, the second limiter is located on the bottom magnet.

Here's what you can see there.

We also see here a voice coil, which is part of the magnetic head unit. The coil and magnets form the VCM drive (Voice Coil Motor, VCM). The drive and the block of magnetic heads form a positioner (actuator) - a device that moves the heads.

The black plastic part with a complex shape is called an actuator latch. It comes in two types: magnetic and air lock. Magnetic works like a simple magnetic latch. Release is carried out by applying an electrical impulse. The air latch releases the BMG after the spindle motor reaches enough speed for the air pressure to move the latch out of the path of the voice coil. The retainer protects the heads from flying out into the work area. If for some reason the latch fails to perform its function (the disk was dropped or hit while it was on), then the heads will stick to the surface. For 3.5“ disks, subsequent activation will simply tear off the heads due to the higher motor power. But the 2.5" has less motor power and the chances of recovering data by freeing the original heads from captivity are quite high.

Now let's remove the magnetic head block.

The precision and smooth movement of the BMG is supported by a precision bearing. The largest part of the BMG, made of aluminum alloy, is usually called a bracket or rocker arm (arm). At the end of the rocker arm there are heads on a spring suspension (Heads Gimbal Assembly, HGA). Usually the heads and rocker arms themselves are supplied by different manufacturers. A flexible cable (Flexible Printed Circuit, FPC) goes to the pad that connects to the control board.

Let's take a closer look at the components of the BMG.

A coil connected to a cable.

Bearing.

The following photo shows the BMG contacts.

The gasket ensures the tightness of the connection. Thus, air can only enter the unit with discs and heads through the pressure equalization hole. This disc has contacts coated with a thin layer of gold to prevent oxidation. But on the electronics board side, oxidation often occurs, which leads to HDD malfunctions. You can remove oxidation from the contacts with an eraser.

This is a classic rocker design.

The small black parts at the ends of the spring hangers are called sliders. Many sources indicate that sliders and heads are the same thing. In fact, the slider helps to read and write information by raising the head above the surface of the magnetic disks. On modern hard drives, the heads move at a distance of 5-10 nanometers from the surface. For comparison, a human hair has a diameter of about 25,000 nanometers. If any particle gets under the slider, this can lead to overheating of the heads due to friction and their failure, which is why cleanliness of the air inside the containment area is so important. Dust can also cause scratches. From them new dust particles are formed, but now magnetic, which stick to the magnetic disk and cause new scratches. This leads to the disc quickly becoming scratched or, in the jargon, “sawed.” In this state, neither the thin magnetic layer nor the magnetic heads work anymore, and the hard drive knocks (click of death).

The read and write head elements themselves are located at the end of the slider. They are so small that they can only be seen with a good microscope. Below is an example of a photograph (on the right) through a microscope and a schematic illustration (on the left) of the relative position of the writing and reading elements of the head.

Let's take a closer look at the surface of the slider.

As you can see, the surface of the slider is not flat, it has aerodynamic grooves. They help stabilize the slider's flight altitude. The air under the slider forms an air cushion (Air Bearing Surface, ABS). The air cushion maintains the flight of the slider almost parallel to the surface of the pancake.

Here's another image of the slider.

The head contacts are clearly visible here.

This is another important part of the BMG that has not yet been discussed. It is called a preamplifier (preamp). A preamplifier is a chip that controls the heads and amplifies the signal coming to or from them.

The preamplifier is placed directly in the BMG for a very simple reason - the signal coming from the heads is very weak. On modern drives it has a frequency of more than 1 GHz. If you move the preamplifier outside the hermetic zone, such weak signal will attenuate greatly on the way to the control board. It is impossible to install the amplifier directly on the head, since it heats up significantly during operation, which makes it impossible for a semiconductor amplifier to work; vacuum tube amplifiers of such small sizes have not yet been invented.

There are more tracks leading from the preamp to the heads (on the right) than to the containment area (on the left). The fact is that a hard drive cannot simultaneously work with more than one head (a pair of writing and reading elements). The hard drive sends signals to the preamplifier, and it selects the head that the hard drive is currently accessing.

Enough about the heads, let's disassemble the disk further. Remove the upper separator.

This is what he looks like.

In the next photo you see the containment area with the top separator and head block removed.

The lower magnet became visible.

Now the clamping ring (platters clamp).

This ring holds the block of plates together, preventing them from moving relative to each other.

Pancakes are strung on a spindle hub.

Now that nothing is holding the pancakes, remove the top pancake. That's what's underneath.

Now it’s clear how space for the heads is created – there are spacer rings between the pancakes. The photo shows the second pancake and the second separator.

The spacer ring is a high-precision part made of a non-magnetic alloy or polymers. Let's take it off.

Let's take everything else out of the disk to inspect the bottom of the hermetic block.

This is what the pressure equalization hole looks like. It is located directly under the air filter. Let's take a closer look at the filter.

Since the air coming from outside necessarily contains dust, the filter has several layers. It is much thicker than the circulation filter. Sometimes it contains silica gel particles to combat air humidity. However, if the hard drive is placed in water, it will get inside through the filter! And this does not mean at all that the water that gets inside will be clean. Salts crystallize on magnetic surfaces and sandpaper instead of plates is provided.

A little more about the spindle motor. Its design is shown schematically in the figure.

A permanent magnet is fixed inside the spindle hub. The stator windings, changing the magnetic field, cause the rotor to rotate.

Motors come in two types, with ball bearings and with hydrodynamic bearings (Fluid Dynamic Bearing, FDB). Ballpoints stopped being used more than 10 years ago. This is due to the fact that their beat is high. In a hydrodynamic bearing, the runout is much lower and it operates much quieter. But there are also a couple of disadvantages. Firstly, it may jam. This phenomenon did not happen with ball ones. If the ball bearings failed, they began to make loud noise, but the information was readable, at least slowly. Now, in the case of a bearing wedge, you need to use a special tool to remove all the disks and install them on a working spindle motor. The operation is very complex and rarely leads to successful data recovery. A wedge can arise from a sudden change in position due to of great importance Coriolis force acting on the axis and leading to its bending. For example, there are external 3.5” drives in a box. The box was standing vertically, it touched it and fell horizontally. It would seem that he didn’t fly far?! But no - the engine is wedged, and no information can be obtained.

Secondly, lubricant can leak out of a hydrodynamic bearing (it is liquid there, there is quite a lot of it, unlike the gel lubricant used in ball bearings) and get onto the magnetic plates. To prevent lubricant from getting on magnetic surfaces, use lubricant with particles that have magnetic properties and capture their magnetic traps. They also use an absorption ring around the site of a possible leak. Overheating of the disk contributes to leakage, so it is important to monitor the operating temperature.

The connection between Russian and English terminology was clarified by Leonid Vorzhev.

Update 2018, Sergey Yatsenko

Reproduction or quotation is permitted provided that reference to the original is maintained.

Each of us is faced with different things every day. computer terms, knowledge about which is superficial, and some terms are completely unfamiliar to us. And why know anything about something that doesn’t concern us or doesn’t bother us. Isn't it? It is a well-known truth: as long as some equipment (including a hard drive) functions normally and without problems, no one will ever bother their head with the intricacies of its operation, and this is of no use.

But, at moments when malfunctions begin during the operation of any system unit device, or simply suddenly need help with a computer, many users immediately take a screwdriver and a book “the basics of computer literacy, or how to resuscitate a computer at home.” And they try to solve the problem on their own, without resorting to the help of a specialist. And most often this ends very badly for their computer.

The concepts of “hard drive” or “hard drive” and their origin

Definition and origin of the concept "hard drive"

So, the topic of our next article, this time will be such a spare part of the system unit as a hard drive. We will consider in detail the very meaning of this concept, briefly recall the history of its development, and dwell in more detail on the internal structure, analyze its main types, interfaces and details of its connection. In addition, let’s look a little into the future, and maybe even almost into the present, and tell you what is gradually replacing the good old screws. Looking ahead, let's say that these are solid-state drives that operate on the principle of USB flash drives - SSD devices.

The world's first hard drive, of the type we are used to seeing and using now, was invented by IBM employee Kenneth Haughton in 1973. This model was called a mysterious combination of numbers: 30-30, just like the caliber of the well-known Winchester rifle. It is not difficult to guess that this is where one of the names came from - Winchester, which is still popular among IT specialists. Or perhaps someone has just read it for the first time.

Let's move on to the definition: a hard drive (or, if it’s convenient for you, a hard drive, hard drive, HDD or screw) is a storage device of a computer (or laptop), on which, using special read/write heads, information is written, stored and deleted as needed .

“How is all this different from simple floppy disks or CD-DVDs?” - you ask. The thing is that, unlike flexible or optical media, here data is recorded on hard (hence the name, although someone may have already guessed it) aluminum or glass plates, on which a thin layer of ferromagnetic material is applied, most often chromium dioxide is used for these purposes.

The entire surface of such rotating magnetic plates is divided into tracks and sectors of 512 bytes each. Some drives have only one such disk. Others contain eleven or more plates, and information is recorded on both sides of each of them.

Internal structure

The design of the hard drive itself consists not only of direct information storage devices, but also of a mechanism that reads all this data. All together, this is the main difference between hard drives and floppy disks. optical drives. And unlike random access memory (RAM), which requires constant food, the hard drive is a non-volatile device. You can safely unplug it and take it with you anywhere. The data is saved on it. This becomes especially important when you need to recover information.

Now let's talk a little about the internal structure of a hard drive. The hard drive itself consists of a sealed block filled with ordinary dust-free air under atmospheric pressure. We do not recommend opening it at home, because... this may damage the device itself. No matter how neat you are, there will always be dust in the room and it can get inside the case. IN professional services, which specialize in data recovery, have a specially equipped “clean room”, inside of which the hard drive is opened.

The device also includes a board with electronic circuit management. Inside the block are the mechanical parts of the drive. One or more magnetic plates are attached to the spindle of the disk rotation drive motor.

The housing also contains a preamplifier-switch for magnetic heads. The magnetic head itself reads or writes information from the surface of one of the sides of the magnetic disk. The rotation speed of which reaches 15 thousand revolutions per minute - this applies to modern models.

When turning on the power, hard processor Disk starts by testing the electronics. If everything is in order, the spindle motor turns on. After a certain critical rotation speed is reached, the density of the air layer flowing between the surface of the disk and the head becomes sufficient to overcome the force of pressing the head against the surface.

As a result, the read/write head “hangs” above the wafer at a tiny distance of only 5-10 nm. The operation of the read/write head is similar to the principle of operation of a needle in a gramophone, with only one difference - it does not have physical contact with the plate, while in a gramophone the needle head is in contact with the record.

When the computer's power is turned off and the disks stop, the head is lowered onto a non-working area of the platter surface, the so-called parking zone. Therefore, it is not recommended to shut down the computer abnormally - simply by pressing the shutdown button or unplugging the power cord from the outlet. This can lead to failure of the entire HDD. Early models had a special software, which initiated the head parking operation.

In modern HDDs, the head is brought into the parking zone automatically when the rotation speed drops below the nominal one or when a command is given to turn off the power. The heads are brought back into the working area only when the rated engine rotation speed is reached.

Surely, the question has already ripened in your inquisitive mind - how sealed is the disk block itself and what is the likelihood that dust or other small particles can leak there? As we already wrote above, they can lead to a malfunction of the hard drive or even to its breakdown and loss of important information.

But don't worry. Manufacturers have provided for everything a long time ago. The disk block with the engine and the heads are located in a special sealed housing - a hermetic block (chamber). However, its contents are not completely isolated from the environment; it is necessary to move air from the chamber to the outside and vice versa.

This is necessary to equalize the pressure inside the block with the outside to prevent deformation of the housing. This balance is achieved using a special device called a barometric filter. It is located inside the hermetic block.

The filter is able to catch the smallest particles, the size of which exceeds the distance between the read/write head and the ferromagnetic surface of the disk. In addition to the above-mentioned filter, there is another one - a recirculation filter. It traps particles that are present in the air flow inside the unit itself. They can appear there as a result of the shedding of magnetic pollination of disks (surely you have ever heard the phrase that “hard has fallen off”). In addition, this filter catches those particles that its barometric “colleague” missed.

HDD connection interfaces

Today, to connect a hard drive to a computer, you can use one of three interfaces: IDE, SCSI and SATA.

Initially, in 1986, the IDE interface was developed only for connecting HDDs. It was then modified to an extended ATA interface. As a result, you can connect not only hard drives, but also CD/DVD drives.

The SATA interface is faster, more modern and more productive than ATA.

In turn, SCSI is a high-performance interface that is capable of connecting various types of devices. This includes not only information storage devices, but also various peripherals. For example, faster SCSI scanners. However, when the USB bus appeared, the need to connect peripherals via SCSI disappeared. So, if you are lucky enough to see him somewhere, then consider yourself lucky.

Now let's talk a little about connecting to the IDE interface. The system can have two controllers (primary and secondary), each of which can connect two devices. Accordingly, we get a maximum of 4: primary master, primary slave and secondary master, secondary slave.

After connecting the device to the controller, you should select its operating mode. It is selected by installing a special jumper (called a jumper) in a certain place in the connector (next to the connector for connecting the IDE cable).

It should be remembered that more fast equipment connects to the controller first and is called master. The second is called slave. The last manipulation will be to connect the power, for this we need to select one of the power supply cables. This information will come in handy if you have a very, very old computer. Since in modern times the need for such manipulations has disappeared.

Connecting via SATA is much easier. The cable for it has the same connectors at both ends. The SATA drive does not have jumpers, so you do not need to select the operating mode of the devices - even a child can handle it. Power is connected using special cable(3.3 V). However, it is possible to connect via an adapter to regular cable nutrition.

Let's give one useful advice: if friends often come to you with their hard drives to copy new films or music (yes, your friends are so harsh that they carry not external HDD, but the usual internal one), and you are already tired of unwinding all the time system unit, we recommend purchasing a special pocket for your hard drive (called Mobile Rack). They are available with both IDE and SATA interfaces. To connect another additional hard drive to your computer, simply insert it into such a pocket and you’re done.

SSD drives - a new stage in development

Already today (and maybe even yesterday) it began next stage in the development of information storage devices. To replace hard drives a new type is coming - SSD. Next we will tell you about it in more detail.

So, SSD ( Solid State Disk) solid state drive, which works on the principle of a USB flash memory. One of its most important distinguishing features from conventional hard drives and optical drives is that its device does not include any moving parts or mechanical components.

Drives of this type, as often happens, were initially developed exclusively for military purposes, as well as for high-speed servers, since the good old hard drives were no longer fast and reliable enough for such needs.

Let's list the most important advantages of SSD:

Firstly, writing information to and reading from an SSD is much faster (tens of times) than from a HDD. Job regular hard drive It slows down the movement of the read/write head very much. And because If the SSD doesn't have it, then there's no problem.
Secondly, due to the simultaneous use of all memory modules installed in the SSD drive, the data transfer speed is much higher.
Thirdly, they are not so susceptible to shock. While hard drives may lose some data when hit or even fail, which is what happens most often - be careful!
Fourthly, they consume less energy, which makes them convenient to use in battery-powered devices - laptops, netbooks, ultrabooks.
Fifthly, this type drives make virtually no noise when operating, whereas when hard drives are operating, we hear the rotation of the disks and the movement of the head. And when they fail, there is generally a strong cracking or knocking sound from the heads.

But let’s not hide: perhaps there are two disadvantages of SSDs - 1) for its certain capacity you will pay much more than for a hard drive with an identical amount of memory (the difference will be several times, although every year it becomes less and less); 2) SSDs have a relatively small, limited number of read/write cycles (i.e., an inherently limited lifespan).

So, we got acquainted with the concept of “hard drive”, examined its structure, operating principle and features of various connection interfaces. We hope that the information provided was easy to understand and, most importantly, useful.

If you have difficulty choosing, if you cannot determine what type of hard drive your motherboard, which interface is suitable or which HDD volume will best suit your needs, then you can always turn to the Compolife computer service for help throughout our service area.

Our specialists will help you with the choice and replacing hard disk. In addition, you can order installation of a new device in your system unit or laptop from us.

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The computer is an indispensable component of human society. It processes pictures, sounds, numbers, words. Fortunately, all information can be saved so as not to be lost when the computer turns off.

The job of a hard drive inside a computer is to store and retrieve information very quickly. The hard drive is a very amazing invention of the computer industry. It can store an astronomical amount of information. This miniature device records a virtually unlimited amount of information using the laws of physics.

If you accidentally produce hard formatting disk, then it will be possible to recover data from it, but it will be time-consuming and expensive.

How does a hard drive work?

To understand, you need to break it. A hard drive consists of five main parts:

It is necessary to protect the disk if we want to use this device for years. What kind of damage could there be? Disc damage is not a metaphor. In such thin layers, the weight of the head is equivalent to the weight of a 747 aircraft, and the weight of a 747 aircraft is comparable to the weight of one hundred thousand passengers flying at a speed of 100 kilometers per hour. Deviation of a fraction of a millimeter and that’s it...

What kind important role The friction force plays when the rocker begins to read information, moving up to 60 times per second. The rocker motor is invisible because this electromagnetic system works on the interaction of two forces of nature - electricity and magnetism. This interaction accelerates the rocker to the speed of light.

Before this we were talking about components, now let's talk about data storage. Data is stored in narrow tracks on the surface of the disk. During production, more than two hundred thousand of these tracks are created on a disc. Each track is divided into sectors. The map of tracks and sectors allows the head to determine where to write or read information. The surface of the disk is smooth and shiny, but upon closer inspection the structure turns out to be more complex. The ferrimagnetic film on the surface remembers all recorded information. The head magnetizes a microscopic area on the film, setting the magnetic moment of such a cell to one of the states “0” or “1”, each such zero and one are called bits. The bit value corresponds to the orientation of the magnetic field, plus or minus, and there is no need to worry about the safety of the data, because the photograph good quality occupies about 29 million such cells and is scattered across 12 different sectors. This sounds impressive, but in reality this incredible number of bits takes up a very small area of the disk's surface. Each square centimeter of surface contains 31 billion bits. This is what I understand memory to be.

The hard drive records and outputs information at speeds that are hard to imagine. Using the laws of magnetism, thin film can remember many different encyclopedias or hundreds of thousands of photographs easily. The hard drive is actually an amazingly miniature device that records any information in small bits. This masterpiece of engineering pushes the boundaries of reasonable physics bit by bit.