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Hard drive, what is it? What does a hard drive consist of and how does it work? Pros and cons of HDD compared to SSD. How does a hard drive work?

Hard drives, or hard drives as they are also called, are one of the most important components of a computer system. Everyone knows about this. But not every modern user even has a basic understanding of how a hard drive functions. The principle of operation, in general, is quite simple for a basic understanding, but there are some nuances, which will be discussed further.

Questions about the purpose and classification of hard drives?

The question of purpose is, of course, rhetorical. Any user, even the most entry-level one, will immediately answer that a hard drive (aka hard drive, aka Hard Drive or HDD) will immediately answer that it is used to store information.

In general, this is true. Do not forget that on the hard drive, in addition to the operating system and user files, there are boot sectors created by the OS, thanks to which it starts, as well as certain labels by which you can quickly find the necessary information on the disk.

Modern models are quite diverse: regular HDDs, external hard drives, high-speed solid-state drives (SSDs), although they are not generally classified as hard drives. Next, it is proposed to consider the structure and principle of operation of a hard drive, if not in full, then at least in such a way that it is enough to understand the basic terms and processes.

Please note that there is also a special classification of modern HDDs according to some basic criteria, among which are the following:

  • method of storing information;
  • media type;
  • way of organizing access to information.

Why is a hard drive called a hard drive?

Today, many users are wondering why they call hard drives related to small arms. It would seem, what could be common between these two devices?

The term itself appeared back in 1973, when the world's first HDD appeared on the market, the design of which consisted of two separate compartments in one sealed container. The capacity of each compartment was 30 MB, which is why the engineers gave the disk the code name “30-30”, which was fully in tune with the brand of the “30-30 Winchester” gun, popular at that time. True, in the early 90s in America and Europe this name almost fell out of use, but it still remains popular in the post-Soviet space.

The structure and principle of operation of a hard drive

But we digress. The principle of operation of a hard drive can be briefly described as the processes of reading or writing information. But how does this happen? In order to understand the principle of operation of a magnetic hard drive, you first need to study how it works.

The hard drive itself is a set of plates, the number of which can range from four to nine, connected to each other by a shaft (axis) called a spindle. The plates are located one above the other. Most often, the materials for their manufacture are aluminum, brass, ceramics, glass, etc. The plates themselves have a special magnetic coating in the form of a material called platter, based on gamma ferrite oxide, chromium oxide, barium ferrite, etc. Each such plate is about 2 mm thick.

Radial heads (one for each plate) are responsible for writing and reading information, and both surfaces are used in the plates. For which it can range from 3600 to 7200 rpm, and two electric motors are responsible for moving the heads.

In this case, the basic principle of operation of a computer hard drive is that information is not recorded just anywhere, but in strictly defined locations, called sectors, which are located on concentric paths or tracks. To avoid confusion, uniform rules apply. This means that the principles of operation of hard drives, from the point of view of their logical structure, are universal. For example, the size of one sector, adopted as a uniform standard throughout the world, is 512 bytes. In turn, sectors are divided into clusters, which are sequences of adjacent sectors. And the peculiarities of the operating principle of a hard drive in this regard are that the exchange of information is carried out by entire clusters (an entire number of chains of sectors).

But how does information reading happen? The principles of operation of a hard magnetic disk drive are as follows: using a special bracket, the reading head is moved in a radial (spiral) direction to the desired track and, when rotated, is positioned above a given sector, and all heads can move simultaneously, reading the same information not only from different tracks , but also from different disks (plates). All tracks with the same serial numbers are usually called cylinders.

In this case, one more principle of hard drive operation can be identified: the closer the reading head is to the magnetic surface (but does not touch it), the higher the recording density.

How is information written and read?

Hard drives, or hard drives, were called magnetic because they use the laws of the physics of magnetism, formulated by Faraday and Maxwell.

As already mentioned, plates made of non-magnetic sensitive material are coated with a magnetic coating, the thickness of which is only a few micrometers. During operation, a magnetic field appears, which has a so-called domain structure.

A magnetic domain is a magnetized region of a ferroalloy strictly limited by boundaries. Further, the principle of operation of a hard disk can be briefly described as follows: when exposed to an external magnetic field, the disk’s own field begins to be oriented strictly along the magnetic lines, and when the influence stops, zones of residual magnetization appear on the disks, in which the information that was previously contained in the main field is stored .

The reading head is responsible for creating an external field when writing, and when reading, the zone of residual magnetization, located opposite the head, creates an electromotive force or EMF. Further, everything is simple: a change in EMF corresponds to one in binary code, and its absence or termination corresponds to zero. The time of change of the EMF is usually called a bit element.

In addition, the magnetic surface, purely from computer science considerations, can be associated as a certain point sequence of information bits. But, since the location of such points cannot be calculated absolutely accurately, you need to install some pre-designated markers on the disk that help determine the desired location. Creating such marks is called formatting (roughly speaking, dividing the disk into tracks and sectors combined into clusters).

Logical structure and principle of operation of a hard drive in terms of formatting

As for the logical organization of the HDD, formatting comes first here, in which two main types are distinguished: low-level (physical) and high-level (logical). Without these steps, there is no talk of bringing the hard drive into working condition. How to initialize a new hard drive will be discussed separately.

Low-level formatting involves physical impact on the surface of the HDD, which creates sectors located along the tracks. It is curious that the principle of operation of a hard drive is such that each created sector has its own unique address, which includes the number of the sector itself, the number of the track on which it is located, and the number of the side of the platter. Thus, when organizing direct access, the same RAM accesses directly to a given address, rather than searching for the necessary information across the entire surface, due to which performance is achieved (although this is not the most important thing). Please note that when performing low-level formatting, absolutely all information is erased, and in most cases it cannot be restored.

Another thing is logical formatting (in Windows systems this is quick formatting or Quick format). In addition, these processes are also applicable to the creation of logical partitions, which are a certain area of ​​the main hard drive that operate on the same principles.

Logical formatting primarily affects the system area, which consists of the boot sector and partition tables (Boot record), file allocation table (FAT, NTFS, etc.) and the root directory (Root Directory).

Information is written to sectors through the cluster in several parts, and one cluster cannot contain two identical objects (files). Actually, the creation of a logical partition, as it were, separates it from the main system partition, as a result of which the information stored on it is not subject to change or deletion in the event of errors and failures.

Main characteristics of HDD

It seems that in general terms the principle of operation of a hard drive is a little clear. Now let's move on to the main characteristics, which give a complete picture of all the capabilities (or shortcomings) of modern hard drives.

The operating principle of a hard drive and its main characteristics can be completely different. To understand what we are talking about, let’s highlight the most basic parameters that characterize all information storage devices known today:

  • capacity (volume);
  • performance (data access speed, reading and writing information);
  • interface (connection method, controller type).

Capacity represents the total amount of information that can be written and stored on a hard drive. The HDD production industry is developing so quickly that today hard drives with capacities of about 2 TB and higher have come into use. And, as it is believed, this is not the limit.

The interface is the most significant characteristic. It determines exactly how the device is connected to the motherboard, which controller is used, how reading and writing are done, etc. The main and most common interfaces are IDE, SATA and SCSI.

Disks with an IDE interface are inexpensive, but the main disadvantages include a limited number of simultaneously connected devices (maximum four) and low data transfer speeds (even if they support Ultra DMA direct memory access or Ultra ATA protocols (Mode 2 and Mode 4). Although it is believed that their use allows you to increase the read/write speed to the level of 16 MB/s, but in reality the speed is much lower. In addition, to use the UDMA mode, you need to install a special driver, which, in theory, should be supplied in complete with motherboard.

When talking about the principle of operation of a hard drive and its characteristics, we cannot ignore which is the successor to the IDE ATA version. The advantage of this technology is that the read/write speed can be increased to 100 MB/s through the use of the high-speed Fireware IEEE-1394 bus.

Finally, the SCSI interface, compared to the previous two, is the most flexible and fastest (write/read speeds reach 160 MB/s and higher). But such hard drives cost almost twice as much. But the number of simultaneously connected information storage devices ranges from seven to fifteen, the connection can be made without turning off the computer, and the cable length can be about 15-30 meters. Actually, this type of HDD is mostly used not in user PCs, but on servers.

Performance, which characterizes the transfer speed and I/O throughput, is usually expressed in terms of transfer time and the amount of sequential data transferred and expressed in MB/s.

Some additional options

Speaking about what the operating principle of a hard drive is and what parameters affect its functioning, we cannot ignore some additional characteristics that may affect the performance or even the lifespan of the device.

Here, the first place is the rotation speed, which directly affects the time of search and initialization (recognition) of the desired sector. This is the so-called latent search time - the interval during which the required sector rotates towards the read head. Today, several standards have been adopted for spindle speed, expressed in revolutions per minute with a delay time in milliseconds:

  • 3600 - 8,33;
  • 4500 - 6,67;
  • 5400 - 5,56;
  • 7200 - 4,17.

It is easy to see that the higher the speed, the less time is spent searching for sectors, and in physical terms, per revolution of the disk before setting the head to the desired platter positioning point.

Another parameter is the internal transmission speed. On external tracks it is minimal, but increases with a gradual transition to internal tracks. Thus, the same defragmentation process, which is moving frequently used data to the fastest areas of the disk, is nothing more than moving it to an internal track with a higher read speed. External speed has fixed values ​​and directly depends on the interface used.

Finally, one of the important points is related to the presence of the hard drive's own cache memory or buffer. In fact, the principle of operation of a hard drive in terms of buffer use is somewhat similar to RAM or virtual memory. The larger the cache memory (128-256 KB), the faster the hard drive will work.

Main requirements for HDD

There are not so many basic requirements that are imposed on hard drives in most cases. The main thing is long service life and reliability.

The main standard for most HDDs is a service life of about 5-7 years with an operating time of at least five hundred thousand hours, but for high-end hard drives this figure is at least a million hours.

As for reliability, the S.M.A.R.T. self-testing function is responsible for this, which monitors the condition of individual elements of the hard drive, carrying out constant monitoring. Based on the collected data, even a certain forecast of the occurrence of possible malfunctions in the future can be formed.

It goes without saying that the user should not remain on the sidelines. So, for example, when working with a HDD, it is extremely important to maintain the optimal temperature regime (0 - 50 ± 10 degrees Celsius), avoid shakes, impacts and falls of the hard drive, dust or other small particles getting into it, etc. By the way, many will It is interesting to know that the same particles of tobacco smoke are approximately twice the distance between the read head and the magnetic surface of the hard drive, and human hair - 5-10 times.

Initialization issues in the system when replacing a hard drive

Now a few words about what actions need to be taken if for some reason the user changed the hard drive or installed an additional one.

We will not fully describe this process, but will focus only on the main stages. First, you need to connect the hard drive and look in the BIOS settings to see if new hardware has been detected, initialize it in the disk administration section and create a boot record, create a simple volume, assign it an identifier (letter) and format it by selecting a file system. Only after this the new “screw” will be completely ready for work.

Conclusion

That, in fact, is all that briefly concerns the basic functioning and characteristics of modern hard drives. The principle of operation of an external hard drive was not fundamentally considered here, since it is practically no different from what is used for stationary HDDs. The only difference is the method of connecting the additional drive to a computer or laptop. The most common connection is via a USB interface, which is directly connected to the motherboard. At the same time, if you want to ensure maximum performance, it is better to use the USB 3.0 standard (the port inside is colored blue), of course, provided that the external HDD itself supports it.

Otherwise, I think that many people have at least a little understood how a hard drive of any type functions. Perhaps too many topics were given above, especially even from a school physics course, however, without this, it will not be possible to fully understand all the basic principles and methods inherent in the technologies for producing and using HDDs.

Today it would not be an exaggeration to say that the vast majority of computer users are familiar with the concept of a “computer hard drive.” They know that every computer has a “memory” that stores all the information such as movies, music, photos, games and programs. However, few of the total number of people who like to stare at the monitor have gone further in understanding this mysterious storage device than the knowledge that “this is such a rectangular thing in which all the files are somehow incomprehensibly stored.” And it is precisely for those readers who want to dig deeper and find out how a hard drive works, as well as understand its structure, that this article was written, in which we will simply and in Russian address these issues.

How does a computer hard drive work?

First, let's take a short excursion into history. The first hard drive was created by IBM almost six decades ago, in 1957. Its volume was 5 megabytes - ridiculous figures by today's standards, but at that time it was a real technological breakthrough. After some time, engineers from the same company created a hard drive with a capacity of 30 MB, and an additional 30 MB in a removable bay. Since this disk structure evoked associations with the marking of the cartridge for the popular Winchester carbine in America - “.30-30” - the designers gave this hard disk the code name “Winchester”. An interesting fact is that in modern times in the West almost no one calls hard drives that way, but in the Russian-speaking environment this name has taken root much more firmly, having also given rise to a convenient abbreviated version - “screw”, which is widely used in colloquial speech.

Hard drive design

Now let's move directly to the highlight of the program and start with its internal structure. The hard drive design consists of the following components.

1. A block of magnetic disks or so-called. “pancakes” (from one to three pieces in one block, located one above the other) are essentially the main element of the hard drive. Each magnetic disk is made of aluminum or glass and coated with a ferromagnetic material, often chromium dioxide. Data is written to the magnetic layer using a magnetic head.
2. Magnetic head block - is a rocker arm connected to an amplifier-commutator microcircuit that amplifies the signal received when reading from a disk. At the tips of the rocker plates there are magnetic heads, which interact with the magnetic disk when performing read and write operations.
3. Spindle motor is a special electric motor that is used to accelerate magnetic disks. Depending on the hard drive model, this figure can reach 15,000 rpm. The design of the engine is based on the use of bearings (ball and hydrodynamic), which allows it to be silent and not create vibrations.
4. The controller board is an integrated circuit whose function is to control the operation of the hard drive by converting the signals transmitted from the magnetic heads into understandable ones for the computer.

How a hard drive works

Having studied the individual components, we can paint a complete picture of what is happening and describe step by step how a computer hard drive works. So, the hard drive is powered - the electronic controller sends a signal to the spindle motor, which begins to rotate magnetic disks firmly fixed to its axis. After reaching the required rotation speed, at which an air gap appears between the pancake and the head, eliminating the possibility of their contact, the rocker brings the heads to them at a “working” distance, which is about 10 nanometers (a billionth of a meter, imagine!).

The first data received from a switched-on hard drive is always service information or so-called. "zero track". It contains information about the status of the hard drive and its characteristics. If for some reason this information cannot be obtained, the device will not boot and will not work.
If the service data is received successfully and does not contain errors, the phase of working with information directly recorded on the disk begins. Most likely, you are already tormented by the question - “how is it recorded?” We answer: magnetic heads, under the influence of current pulses, are capable of magnetizing sections of the disk, thereby forming bits (logical “zeros” and “ones”, different from each other in the direction of the magnetic moment). In other words, all the information on a computer’s hard drive is its differently magnetized sections, which, after being converted into standardized signals, are recognized by the computer and presented to the user in a form that is understandable to him. It should be noted that these areas are strictly structured - they represent the so-called. "tracks", that is, ring-shaped areas on the surface of a magnetic disk.

It is important to note that the head block is one piece, so all the heads in it move synchronously - therefore, they are always located over the same track of each individual pancake. Based on this, the tracks form a cylinder in the vertical plane. Moreover, each track consists of segments called “sectors”. When writing information to these sectors, magnetic heads change their magnetic field, and when reading information, they simply capture it. Having understood the physical structure of data storage, we can conclude that the volume of a hard drive is equal to the product of the number of cylinders, the number of heads and the number of sectors.

Formatting your hard drive

A story about how a computer hard drive works cannot be called complete if it does not touch on the topic of formatting. Formatting is a special process of marking up the information storage area of ​​a hard drive, the essence of which is to create certain structures for accessing this data, for example a file system, by recording certain service information. In this case, previously stored data is destroyed (however, not always irretrievably). Most often, formatting is performed when installing (or reinstalling) an operating system on a computer, since the best option for this is a “clean”, formatted disk, cleared of data from the previous OS. In order not to lose the necessary information, the “screw”, as a rule, is first logically divided into several partitions - in this case, formatting will only be required for the partition on which the OS will be installed, while the data on the remaining partitions will remain untouched, which is a very user-friendly approach .

The hard drive is almost one of the most important elements of a modern computer. Since it is designed primarily for long-term storage of your data, this can be games, movies and other large files stored on your PC. And it would be a shame if it could suddenly break down, as a result of which you could lose all your data, which can be very difficult to recover. And in order to properly operate and replace this element, you need to understand how it works and what a hard drive is.


From this article you will learn about the operation of a hard drive, its components and technical characteristics.

Typically, the main elements of a hard drive are several round aluminum platters. Unlike floppy disks (forgotten floppy disks), they are difficult to bend, hence the name hard disk. In some devices they are installed non-removable and are called fixed (fixeddisk). But in ordinary desktop computers and even some models of laptops and tablets, they can be replaced without problems.

Figure: Hard drive without top cover

The note!

Why are hard drives sometimes called hard drives and what do they have to do with firearms? Sometime in the 1960s, IBM released what was then a high-speed hard drive with development number 30-30. Which coincided with the designation of the famous Winchester rifled weapon, and therefore this term soon became entrenched in computer slang. But in fact, hard drives have nothing in common with real hard drives.

How does a hard drive work?

Recording and reading of information located on the concentric circles of the hard disk, divided into sectors, is carried out using universal write/read heads.

Each side of the disk has its own track for writing and reading, but the heads are located on a common drive for all disks. For this reason, the heads move synchronously.

YouTube Video: Open Hard Drive Operation

Normal drive operation does not allow contact between the heads and the magnetic surface of the disk. However, if there is no power and the device stops, the heads still fall onto the magnetic surface.

During operation of the hard drive, a small air gap forms between the surface of the rotating platter and the head. If a speck of dust enters this gap or the device is shaken, there is a high chance that the head will collide with the rotating surface. A strong impact can cause the head to fail. This output may result in several bytes being corrupted or the device being completely inoperable. For this reason, in many devices the magnetic surface is alloyed, after which a special lubricant is applied to it to cope with periodic shaking of the heads.

Some modern drives use a loading/unloading mechanism that prevents the heads from touching the magnetic surface even if the power is lost.

High and low level formatting

Using high-level formatting allows the operating system to create structures that make it easier to work with files and data stored on the hard drive. All available partitions (logical drives) are provided with a volume boot sector, two copies of the file allocation table, and a root directory. Through the above structures, the operating system manages to allocate disk space, track the location of files, and also bypass damaged areas on the disk.

In other words, high-level formatting comes down to creating a table of contents for the disk and file system (FAT, NTFS, etc.). “Real” formatting can only be classified as low-level formatting, during which the disk is divided into tracks and sectors. Using the DOS FORMAT command, a floppy disk undergoes both types of formatting at once, while a hard disk undergoes only high-level formatting.

In order to perform low-level formatting on a hard drive, you need to use a special program, most often provided by the disk manufacturer. Formatting floppy disks using FORMAT involves performing both operations, while in the case of hard disks, the above operations should be performed separately. Moreover, the hard drive undergoes a third operation - the creation of partitions, which are a prerequisite for using more than one operating system on one PC.

The organization of several partitions makes it possible to install on each of them its own operating infrastructure with a separate volume and logical drives. Each volume or logical drive has its own letter designation (for example, drive C, D or E).

What does a hard drive consist of?

Almost every modern hard drive includes the same set of components:

disks(their number most often reaches 5 pieces);

read/write heads(their number most often reaches 10 pieces);

head drive mechanism(this mechanism sets the heads to the required position);

disk drive motor(a device that causes disks to rotate);

air filter(filters located inside the drive housing);

printed circuit board with control circuits(through this component the drive and controller are managed);

cables and connectors(HDD electronic components).

A sealed box - HDA - is most often used as a housing for disks, heads, a head drive mechanism and a disk drive motor. Usually this box is a single unit that is almost never opened. Other components not included in the HDA, which include configuration elements, printed circuit board and front panel, are removable.

Automatic head parking and control system

In the event of a power failure, a contact parking system is provided, the task of which is to lower the bar with the heads onto the discs themselves. Regardless of the fact that the drive can withstand tens of thousands of ascents and descents of the read heads, all this must happen in areas specially designated for these actions.

During constant ascents and descents, inevitable abrasion of the magnetic layer occurs. If the drive is shaken after wear and tear, damage to the disk or heads is likely to occur. To prevent the above troubles, modern drives are equipped with a special loading/unloading mechanism, which is a plate that is placed on the outer surface of the hard drives. This measure prevents the head from touching the magnetic surface even if the power is turned off. When the voltage is turned off, the drive automatically “parks” the heads on the surface of the inclined plate.

A little about air filters and air

Almost all hard drives are equipped with two air filters: a barometric filter and a recirculation filter. What distinguishes the above filters from replaceable models used in older generation drives is that they are placed inside the case and are not expected to be replaced until the end of their service life.

Old disks used the technology of constantly moving air in and out of the case, using a filter that needed to be changed periodically.

The developers of modern drives had to abandon this scheme, and therefore the recirculation filter, which is located in the sealed HDA case, is used only to filter the air inside the box from the smallest particles trapped inside the case. Regardless of all precautions taken, small particles still form after repeated landings and takeoffs of the heads. Taking into account the fact that the drive housing is sealed and air is pumped inside it, it continues to function even in highly polluted environments.

Interface connectors and connections

Many modern hard drives are equipped with several interface connectors designed to connect to the power source and to the system as a whole. As a rule, the drive contains at least three types of connectors:

interface connectors;

power supply connector;

ground connector.

The interface connectors deserve special attention, since they are designed for the drive to receive/transmit commands and data. Many standards do not exclude the possibility of connecting several drives to one bus.

As mentioned above, HDD drives can be equipped with several interface connectors:

MFM and ESDI- extinct connectors used on the first hard drives;

IDE/ATA- a connector for connecting storage devices, which has long been the most common due to its low cost. Technically, this interface is similar to the 16-bit ISA bus. The subsequent development of IDE standards contributed to an increase in data exchange speed, as well as the emergence of the ability to directly access memory using DMA technology;

Serial ATA- a connector that replaced IDE, which is physically a unidirectional line used for serial data transfer. Being in compatibility mode is similar to the IDE interface, however, the presence of a “native” mode allows you to take advantage of an additional set of capabilities.

SCSI- a universal interface that was actively used on servers for connecting HDDs and other devices. Despite good technical performance, it has not become as widespread as IDE due to its high cost.

SAS- serial analog SCSI.

USB- an interface that is necessary for connecting external hard drives. Information exchange in this case occurs via the USB Mass Storage protocol.

FireWire- a connector similar to USB, required for connecting an external HDD.

Fiber Channel-interface used by high-end systems due to high data transfer rates.

Hard drive quality indicators

Capacity— the amount of information the drive can hold. This figure in modern hard drives can reach up to 4 terabytes (4000 gigabytes);

Performance. This parameter has a direct impact on response time and average information transfer speed;

Reliability– an indicator determined by the mean time between failures.

Physical Capacity Limits

The maximum amount of capacity used by a hard drive depends on a number of factors, including the interface, drivers, operating system and file system.

The first ATA drive, released in 1986, had a capacity limit of 137 GB.

Different BIOS versions also contributed to reducing the maximum capacity of hard drives, and therefore systems built before 1998 had a capacity of up to 8.4 GB, and systems released before 1994 had a capacity of 528 MB.

Even after solving the problems with the BIOS, the capacity limitation of drives with an ATA connection interface remained; its maximum value was 137 GB. This limitation was overcome through the ATA-6 standard, released in 2001. This standard used an expanded addressing scheme, which, in turn, contributed to an increase in storage capacity to 144 GB. Such a solution made it possible to introduce drives with PATA and SATA interfaces, whose storage capacity is higher than the specified limit of 137 GB.

OS restrictions on maximum volume

Almost all modern operating systems do not impose any restrictions on such an indicator as the capacity of hard drives, which cannot be said about earlier versions of operating systems.

For example, DOS did not recognize hard drives whose capacity exceeded 8.4 GB, since access to the drives in this case was performed through LBA addressing, while in DOS 6.x and earlier versions only CHS addressing was supported.

There is also a hard drive capacity limitation when installing Windows 95. The maximum value for this limit is 32 GB. In addition, updated versions of Windows 95 only support the FAT16 file system, which, in turn, imposes a 2 GB limit on partition sizes. It follows from this that if you use a 30 GB hard drive, it must be divided into 15 partitions.

Windows 98 operating system limitations allow the use of larger hard drives.

Characteristics and parameters

Each hard drive has a list of technical characteristics, according to which its usage hierarchy is established.

The first thing you should pay attention to is the type of interface used. Recently, every computer has begun to use SATA.

The second equally important point is the amount of free space on the hard drive. Its minimum value today is only 80 GB, while the maximum is 4 TB.

Another important characteristic when purchasing a laptop is the hard drive form factor.

The most popular in this case are models whose size is 2.5 inches, while in desktop PCs the size is 3.5 inches.

You should not neglect the spindle rotation speed, the minimum values ​​are 4200, the maximum is 15000 rpm. All of the above characteristics have a direct impact on the speed of the hard drive, which is expressed in MB/s.

Hard drive speed

Of no small importance are the speed indicators of the hard drive, which are determined by:

Spindle speed, measured in revolutions per minute. Its task does not include directly identifying the real exchange speed; it only allows you to distinguish a faster device from a slower device.

Access time. This parameter calculates the time spent by the hard drive from receiving a command to transmitting information over the interface. Most often I use the average and maximum values.

Head positioning time. This value indicates the time it takes for the heads to move and set up from one track to another track.

Bandwidth or disk performance during sequential transfer of large amounts of data.

Internal data transfer rate or the speed of information transmitted from the controller to the heads.

External baud rate or the speed of information transmitted via the external interface.

A little about S.M.A.R.T.

S.M.A.R.T.– a utility designed to independently check the status of modern hard drives that support the PATA and SATA interfaces, as well as those running on personal computers with the Windows operating system (from NT to Vista).

S.M.A.R.T. calculates and analyzes the state of connected hard drives at equal intervals of time, regardless of whether the operating system is running or not. After the analysis has been carried out, the diagnostic result icon is displayed in the right corner of the taskbar. Based on the results obtained during S.M.A.R.T. diagnostics, the icon may indicate:

For the excellent condition of every hard drive connected to the computer that supports S.M.A.R.T. technology;

The fact that one or more health indicators do not meet the threshold value, while the Pre-Failure / Advisory parameters have a zero value. The above state of the hard drive is not considered pre-failure, however, if this hard drive contains important information, it is recommended to save it on another medium as often as possible or replace the HDD.

The fact that one or more status indicators do not meet the threshold value, while the Pre-Failure / Advisory parameters have an active value. According to hard drive developers, this is a pre-emergency state, and it is not worth storing information on such a hard drive.

Reliability factor

An indicator such as data storage reliability is one of the most important characteristics of a hard drive. The failure rate of a hard drive is once every hundred years, from which we can conclude that HDD is considered the most reliable source of data storage. At the same time, the reliability of each disk is directly influenced by the operating conditions and the device itself. Sometimes manufacturers supply the market with a completely “raw” product, and therefore you cannot neglect backup and completely rely on the hard drive.

Cost and price

Every day the cost of HDD is becoming less and less. For example, today the price of a 500 GB ATA hard drive averages $120, compared to $1,800 in 1983 for a 10 MB hard drive.

From the above statement we can conclude that the cost of HDDs will continue to fall, and therefore in the future everyone will be able to purchase fairly capacious disks at reasonable prices.

Many users are interested in the hard drive device. And for good reason, because today the most common storage device on a computer is the HDD. Next, the principles of its operation and structure will be discussed.


A Winchester is essentially like a record player. It also contains the platters and read heads. However, the HDD device is more complex. If we disassemble the hard drive, we will see that the plates are mostly metal and covered with a magnetic layer. This is where data is written. Depending on the volume of the hard drive, there are from 4 to 9 plates. They are mounted on a shaft, which is called a “spindle” and has a high rotation speed from 3600 to 10000 rpm for consumer products.

Next to the wafer block there is a read head block. The number of heads is determined by the number of magnetic disks, namely one for each disk surface. Unlike a hard disk player, the head does not touch the surface of the platters, but hovers above it. This eliminates mechanical wear. Since the plates have a high rotation speed, and the heads must be at an extremely small constant distance above them, it is very important that nothing can get into the housing. After all, the slightest speck of dust can cause physical damage. That is why the mechanical part is hermetically sealed with a casing, and the electronic part is taken outside.

Some users are interested in how to disassemble a hard drive. You need to understand that disassembling a working drive involves breaking its seal. And this, in turn, will render it unusable. Therefore, you should not do this unless you are ready to lose all the data on the storage medium. If you don’t have an urgent need to open the drive, but are just curious about what a hard drive is made of, you can look at a photo of a disassembled HDD.

That is why hard drives on magnetic disks are disassembled during repair and assembled in a special laminar flow hood. Using a highly purified air supply system and tightness, it maintains the environment necessary for such work. By disassembling your disk at home, you will definitely render it inoperable.

When inoperative, the read heads are located next to the wafer block. This is also called “parking position”. A special device brings the heads into the working area only when the disk has accelerated to the required speed. They all move together, not each one separately. This allows you to have quick access to all data.

The electronic board, or controller, is usually attached to the bottom of the hard drive. Nothing protects it, and this makes it quite vulnerable to mechanical and thermal damage. It is she who controls the mechanics. The laptop hard drive differs from the standard 3.5-inch only in size. The principle of operation of a hard drive is exactly the same. They can differ only in the number of magnetic pancakes and storage capacity.

As you can see, the hard drive device is subject to shock, shock, scratches, significant temperature changes and power surges. And this makes it not a completely reliable information carrier. It is because of this that the hard drive on a laptop fails more often than on a desktop PC. After all, portable devices are constantly shaken, sometimes dropped, taken out into the cold or placed in the sun. And this, in turn, negatively affects the hard drive.

To extend the life of the HDD, do not expose it to drops or shocks, make sure that there is sufficient ventilation of the case, and perform any manipulations with the disk only when the power is turned off. These shortcomings have led to the emergence of a new type of SSD hard drive. They are gradually replacing HDDs, which once looked like great storage media.

Logical device


We found out what a hard drive looks like inside. Now we will analyze its logical structuring. Data is written to the computer's hard drive on tracks that are divided into specific sectors. The size of each sector is 512 bytes. Consecutive sectors are combined into a cluster.

When installing a new HDD, you need to format it, otherwise the computer simply will not see the free space on the drive. Formatting can be physical or logical. The first involves dividing the disk into sectors. Some of them may be defined as “bad”, that is, unsuitable for recording data. In most cases, the drive is already formatted in this way before being sold.

Logical formatting involves creating a logical partition of the hard drive. This allows you to significantly simplify and optimize your work with information. A specific area of ​​the drive is allocated for a logical partition (or, as it is also called, a “logical disk”). You can work with it as with a separate hard drive. To understand how a hard drive works with its partitions, it is enough to visually divide the hard drive into 2-4 parts, depending on the number of logical volumes. Each volume can have its own formatting system: FAT32, NTFS or exFAT.

Technical data


HDDs differ from each other according to the following data:

  • volume;
  • spindle rotation speed;
  • interface.

Today, the average hard drive capacity is 500-1000 GB. It determines the amount of information that you can write to the media. The spindle speed will determine how quickly you can access data, that is, read and write information. The most common interface is SATA, which replaced the already obsolete and slow IDE. They differ from each other in bandwidth and type of connector connected to the motherboard. Note that the disk of a modern laptop can only have a SATA or SATA2 interface.

This article examined how a hard drive works, its operating principles, technical data and logical structure.