Hard drives, or, as they are also called, hard drives, are one of the most important components computer system. Everyone knows about this. But not every modern user even in principle understands how it functions. HDD. 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, will immediately answer that the 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 quite varied: regular HDDs, external hard disks, high speed solid state SSD drives, although it is not customary to classify them specifically as hard drives. Next, it is proposed to consider the structure and principle of operation of the 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? Operating principles of the drive hard magnetic disks look like this: using a special bracket, the reading head moves 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. Then everything is simple: the change in EMF corresponds to unity in binary code, and its absence or termination is 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-designed 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, on which the performance or even the service life of the device may depend.

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 appearance of possible malfunctions further.

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 at it BIOS settings, whether new equipment has been identified, in the disk administration section, initialize 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. Principle of operation external hard disk was not considered fundamentally 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 painted blue), of course, provided that the external HDD supports him.

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 we will talk about what HDD drives are, what they are, and consider their characteristics. Let's find out which of them are the best, and which HDDs you shouldn't buy.

A hard drive is an information storage device that is used in computers and laptops to install an operating system, drivers, programs on it, as well as to store all kinds of user files.

Hard drive design

HDD - half mechanical, half electronic device, consisting of magnetic plates, read heads, spindle (motor), and control board. The spindle on which the magnetic plates are attached spins them up to several thousand rpm. in a minute. It is believed that the higher the spindle torque, the higher the reading speed. Although important factors include: random access time and recording density. HDDs differ in speed, capacity, and of course reliability. This parameter is guaranteed by the manufacturer.

Which manufacturing companies are better?

Samsung drives are considered the most reliable and fastest. Hitachi also produces very good wheels, but their speed is lower. HDDs from companies are of average quality Western Digital. It turned out that this company initially began to produce its products in cheap factories that did not have high-quality equipment. The lowest quality production of devices of this type from well-known brands is the once leading American electronics company Seagate. Well, Fujitsu and Toshiba companies now cannot boast of the quality of hard drive production.

Therefore, when choosing to purchase an HDD, it is better to choose either Samsung or Hitachi. They differ in their dimensions. HDDs with a disk width of 3.5 (inches) are installed on computers, and 2.5 (inches) on laptops.
Hard drive speed system unit the speed of a computer is more than 7000 rpm, but there are HDDs on sale with a performance of no higher than 5500 rpm. Such low-speed copies are not worth buying. But laptop drives with a rotation speed of 5400 rpm. They work much quieter and don't get so hot.

Buffer hard drive called cache memory, and serves to speed it up. It ranges from 32 to 128 MB. Although 32 MB. will be enough for its normal operation. Read and write speed is one of the most important parameters, which greatly influences working productivity devices.

Information exchange speed

A good indicator for a HDD is considered to be a read speed of 110 - 140 MB/s. You should not buy a HDD with a speed not exceeding 100 MB/s. Random access time is the second important indicator of hard drive performance, after reading and writing. It is believed that the smaller this parameter, the better quality devices. It mainly affects copying and reading small files. Pretty good if the HDD access time is 13 - 14 ms. Carriers of this type come with two types of connectors. These are SATA 2 (earlier) and SATA 3. These connectors are compatible with each other, so this does not in any way affect the operation of the drives or their speed. Hard drives haven't changed at all over the past ten years. Therefore, the price for them remained approximately at the same level.

WindowsTune.ru

What is HDD in a computer?

IN various programs Monitoring the operation of a computer, you can come across such a designation as HDD. On most computer cases there is a periodically flashing light with the same signature. What does this abbreviation mean?

HDD

HDD, also known as Hard Disk Drive, is nothing more than a hard drive. The blinking light, by the way, blinks for a reason - you can always determine from it whether the hard drive is working at all, or whether the system is not accessing it (then it just hangs, but there can be many reasons for this, and so you know more deep symptoms are if the light does not light up at all). If the light is constantly on, this indicates an excessive load on the computer - you will notice this by its greatly reduced performance. In such a situation, we advise you to simply close some programs - then the number of accesses to the hard drive will decrease, and the performance of running programs will increase.

AskPoint.org

hdd what is it?

HDD, hard drive, hard drive... All these words mean the same component of a modern personal computer, without which it is impossible to imagine it.

Previously, all information on computers, which at that time were called computers, was stored on devices called punched tapes. What is punched paper tape? Essentially, it is a piece of cardboard paper with special holes made in it. But this is the “stone age” of computers. The next stage in the development of personal computers was a technology called magnetic recording. It is this principle that underlies the operating technologies of modern hard drives. The main difference between hard drives of the past and modern models for ordinary users is the amount of information that can be recorded on one medium. If earlier this volume was measured only in kilobytes, today we are dealing with terabytes. Increasing the volume of stored information is one of the main achievements of current HDDs.

Why and what is HDD needed for?

Why do you need a hard disk (HDD) and how is it used directly by the computer operating system itself? As a rule, any computer stores some kind of information, and a hard drive is the very device on which the information is stored. Today this is a very important function for any computer (storing information on digital media), since without a hard drive we, users of personal computers, would have to have constant access to the Internet or local network, and computers without such capabilities would lose a significant share of their functionality.

In more “scientific” terms, a hard drive is a storage component of any PC. The main task of this component is to store information for a long time. Hard drive, as opposed to computer RAM ( random access memory), is not memory, called volatile. What does it mean? Let's imagine that you were working on a computer with some document, saved it, and then, of course, turned off the computer. If HDD memory were volatile, then all the information you saved would be irretrievably lost. Why? The thing is that for normal operation of volatile memory, a constantly switched-on power supply is required. It is on this principle that computer RAM works, but memory on hard drives- no, because it is not volatile. For the same reason, this type of memory is the best for storing any information, be it documents, photographs, videos, etc. By the way, operating system, as a rule, is installed on the hard drive in a partition specially designed for this purpose. Of course, all of the above does not mean at all that information is stored on this type of device for decades; on the contrary, it needs to be periodically “cleaned,” that is, unnecessary and redundant information must be removed.

What do the terms HDD, hard drive and hard drive mean?

What does HDD mean? The answer is: HDD is a hard disk drive that uses a magnetic operating principle. Abbreviation with in English(hard disk drive) is translated as hard drive. You can also add the word magnetic to this abbreviation, which means magnetic.

By the way, why exactly hard? What is a computer hard drive? Why not soft? There are no secrets here either. The thing is that inside this type of device there are special plates. The plates are hard, in fact, this is the explanation of this name. Perhaps we can say a few words about floppy disks, which appeared at about the same time as hard drives. So these floppy disks, namely their magnetic disks, were soft. So everything is logical and natural.

As for the word hard drive, everything is somewhat more complicated. The reason for the appearance of this name, oddly enough, is intertwined with the designation of the real rifle itself. In 1973, the world saw the HDD 3340 model, which had the engineering designation 30-30 (Two modules of 30 MB each). This designation echoed the name of the 30-30 Winchester cartridges. It's simple.

What do these devices look like inside a personal computer?

Now the most popular HDD models have sizes of 2.5 or 3.5 inches. The latter are used in regular PCs, and the 2.5-inch form factor is intended for laptops and portable versions of devices.

The first thing worth saying is that in the world of computer technology everything is improving, and quite quickly, and the situation with our type of device is no exception. What does a hard drive look like on a computer today? Now the most popular HDD models have sizes of 2.5 or 3.5 inches. The latter are used in regular PCs, and the 2.5-inch form factor is intended for laptops and portable versions of devices. In older PCs you can also find disks with other sizes, but they are outdated and modern computers usually not used. Which sizes are already outdated? By and large - everything except the above. Previously, HDDs had a format of 8 and 5.25 inches.

Memory capacity of modern hard drives.

For most users, memory size seems to be a key indicator in choosing the most suitable model for use. Speaking about computers in Russian, we can say it bluntly - no one cares about all the technical characteristics (noise, speed) except one. As you may have guessed, this is exactly the amount of information that can fit on a disk. It doesn’t matter that a hard drive can be noisy and slow, the main thing is how much it can fit. This is what worries the vast majority of users. Moreover, many other characteristics in the eyes of ordinary people do not look so significant, but the number free space- the main indicator. Of course, there are users who pay attention to noise, power consumption and other secondary characteristics of any hard drive, but they are in the minority.

In general, when choosing memory for your computer, it is worth remembering one trick from manufacturers. When indicating the amount of memory of a device, they round up all values, so the actual amount of memory will be slightly less than indicated on the package. The thing is that manufacturers round the figures in such a way that one kilobyte ends up being 1000 bytes, not 1024. Hence the “error”. Is it possible to somehow fight this? By and large, no, but it can be used, and we tell you how to do it in Russian: try to use this fact (rounding in favor of the manufacturer) to your advantage: bargain with the seller, pointing out the smaller amount of real hard drive memory instead of the declared one. What if you can save money? Buy yourself a cookie)

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.

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

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 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 gets into 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 supplied boot sector volume, two copies of the file allocation table, and the 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 produce low level formatting on your hard drive, you must use special program, most often provided by the disc 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 case);

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, head drive mechanism and 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 a heavily polluted environment.

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 speed data transmission.

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 disk capacity limitation when installing Windows 95. The maximum value of this limitation is 32 GB. In addition, updated Windows versions 95 is only supported file system FAT16, 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 speed transmitted information 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 PATA and SATA interfaces, as well as operating in personal computers from the operating room Windows 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 hard disk is not considered pre-crash, 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

Such an indicator as data storage reliability is one of the most important characteristics 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 neglect backup and you cannot 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.

Hard drive, hard drive or just a screw, hard disk, hdd (Hard Disk Drive) - this data storage device has several names and is the main storage device for storing information in all modern computers, laptops and servers. It is on this device that all your photos, videos, music, films are recorded, and the operating system of the computer itself is recorded on it. Nowadays, SSD drives and hybrid SSHD drives are becoming increasingly widespread; we will talk about them and their pros and cons in a separate article.

What kind of discs are there?

In the store today you can find hard drives with different parameters, how do they differ? Let's try to understand the main differences and highlight several characteristics of the drives.

Form factor (size)

The parameter shows the width of the hard drive in inches. The main width is 3.5 inches and 2.5 inches, used in modern computers and laptops, as well as in external portable and stationary drives and network storage.

For landline home computer standard size is 3.5 inches, modern cases contain 2.5-inch drive bays, they are mainly intended for SSD installation disk, there is no particular point in installing 2.5-inch disks in a computer instead of a 3.5-inch disk, only in very compact cases, for example micro-ATX.

In laptops, on the contrary, saving space is very important and they use 2.5-inch form factors. There are disks smaller size- 1.8 inches, 1.3 inches, 0.8 inches, but in modern devices you won't see them anymore.

Capacity (Why is the disk capacity less than stated?)

A parameter that directly determines how much information we can record and store on our computer or laptop. Manufacturers indicate the capacity at the rate of 1 kilobyte = 1000 bytes, but computers calculate differently 1 KB = 1024 bytes, hence the confusion among users encountering this for the first time and the larger the volume, the greater the difference in the final volume. Now the volume of disks is measured in terabytes, which is more than enough to store a collection of not only photos, but also music and films.

Interface

You will find drives with a SATA connector in all modern devices today. The only difference is the data transfer speed.

SATA hard drive connector

ATA aka PATA (IDE)

Disks with this interface are no longer produced or installed in modern devices, but you can find them in older computers. Initially, the interface was called ATA, but after the appearance of the more modern and high-speed SATA in 2003, it was renamed PATA.

PATA (ATA) aka IDE

The name IDE was coined by WD (Western Digital) in 1986 for marketing reasons when it developed the first version of this connection standard.

SCSI and SAS

Disks with SAS interface are used in server equipment. They replaced the SCSI interface. The average user should only know that they are intended for completely different tasks and are not used in home PCs.

SCSI

Spindle speed

The number of spindle revolutions (the axis on which the plate or several plates inside the disk rotate). There are several standards; in home computers and laptops, disks with rotation speeds of 5400, 7200 and 10000 rpm are used; on server equipment there are rotation speeds of 15000 rpm. The parameter affects the time of access to information.

There are several more parameters, such as noise level, time between failures, etc. in modern drives, these parameters correspond to standard criteria and do not differ significantly; we will pay attention to them when we compare and select hard drives.

External drives (portable or stationary)

These are already familiar drives, enclosed in an external plastic or metal box in which a control board or even an entire mini-PC on the board is installed. These drives have various outputs, the main connectors are mini-USB, micro-USB, micro-USB 3.0, fireware and others, portable models powered by USB connector. Stationary ones have a separate power cable. Modern models of external drives can work with wireless network wifi Now on sale you can find network storages with several disks in one case, which can be connected into RAID arrays. We will talk separately about all these devices in future articles.

What is HDD, hard drive and hard drive - these words are different widely used terms for the same device that is part of the computer. Due to the need to store information on a computer, information storage devices such as a hard drive appeared and became an integral part of a personal computer.

Previously on the first computers information was stored on punched tapes - this is cardboard paper with holes punched in it; the next step of man in the development of a computer was magnetic recording, the principle of operation of which is preserved in today's hard drives. Unlike today's terabyte HDDs, the information to be stored on them numbered tens of kilobytes, which is insignificant compared to today's information.

Why do you need a HDD and its functionality?

HDD is a computer's permanent storage device, that is, its main function is long-term data storage. HDD, unlike RAM, is not considered volatile memory, that is, after turning off the power from the computer, and then, as a result, from the hard drive, all information previously stored on this drive will certainly be preserved. It turns out that the hard drive serves best place on your computer for storage personal information: files, photographs, documents and videos will obviously be stored on it for a long time, and the stored information can be used in the future for your needs.

ATA/PATA (IDE)- this parallel interface serves not only to connect hard drives, but also disk reading devices - optical drives. Ultra ATA is the most advanced representative of the standard and has a possible data usage speed of up to 133 megabytes per second. This method of data transfer is considered very outdated and today is used in outdated computers, on modern motherboards The IDE connector can no longer be found.

SATA (Serial ATA)- is a serial interface, which has become a good replacement for the outdated PATA and, unlike it, it is possible to connect only one device, but on budget motherboards there are several connectors for connection. The standard is divided into revisions that have different speeds data transfer/exchange:

• SATA has a data transfer speed of up to 150 Mb/s. (1.2 Gbit/s);
• SATA rev. 2.0 - in this revision, the data exchange speed in comparison with the first SATA interface has increased 2 times to 300 MB/s (2.4 Gbit/s);
• SATA rev. 3.0 - data exchange for the revision has become even higher up to 6 Gbit/s (600 MB/s).

All of the above-described connection interfaces of the SATA family are interchangeable, but by connecting, for example, a hard drive with a SATA 2 interface to the motherboard connector SATA boards, data exchange with the hard drive will be based on the highest revision, in this case SATA revision 1.0.