Hdd what does vk mean. Hard drive - what is it? Features of hard drives

How is a hard drive arranged? What are hard drives? What role do they play in a computer? How do they interact with other components? What parameters to consider when choosing and buying hard drive you will learn from this article.

HDD- short name for " Hard Disk Drive". You will also meet English HDD- and slang Winchester or abbreviated Screw.

V computer hard The disk is responsible for storing data. operating room Windows system, programs, movies, photos, documents, all the information that you download to your computer is stored on your hard drive. And the information in the computer is the most valuable thing! If the processor or video card fails, they can be bought and replaced. But lost family photos from last summer's vacation, or a year's worth of accounting data for a small business, are not so easy to recover. Therefore, the reliability of data storage is given special attention.

Why is a rectangular metal box called a disc? To answer this question, we need to look inside and find out how a hard drive works. In the picture below you can see what parts a hard drive consists of and what functions each part performs. Click to enlarge. (Taken from itc.ua)

I suggest you also watch an excerpt from the show Discovery Channel about how a hard drive works and works.

Three more facts you need to know about hard drives.

1. HDD the slowest part of a computer. When the computer freezes, pay attention to the hard drive activity indicator. If it blinks frequently or stays on, then the hard drive is executing the commands of one of the programs, while all the others are idle, waiting for their turn. If the operating system does not have enough high-speed RAM to run the program, it uses hard disk space, which greatly slows down the entire computer. Therefore, one way to increase the speed of your computer is to increase the amount of RAM.
2. The hard drive is also the most fragile part of a computer. As you learned from the video, the engine spins the disk up to several thousand revolutions per minute. In this case, the magnetic heads "hover" above the disk in air flow created by a spinning disk. The distance between the disk and heads in modern devices is about 10 nm. If the disk is subjected to shock or shock at this point, the head may touch the disk and damage the surface with data stored on it. As a result, the so-called bad blocks" - unreadable areas, due to which the computer cannot read any file or boot the system. In the off state, the heads "park" outside working area and impact overloads are not so scary hard drive. Please do backups important data!
3. The capacity of the hard drive is often slightly smaller than what the seller or manufacturer specifies. The reason is that manufacturers indicate the size of the disk based on the fact that there are 1,000,000,000 bytes in one gigabyte, while there are 1,073,741,824 of them.

Buying a hard drive

If you decide to increase the amount of information storage in your computer by connecting an additional hard drive or replacing the old one with a larger one, what do you need to know when buying?

First, look under the cover of your computer's system unit. You need to find out which interface connecting hard disk is supported by the motherboard. By far the most widely used standards SATA and outliving its age IDE. They are easy to distinguish by appearance. The picture on the left shows a fragment of the motherboard, which is equipped with both types of connectors, but yours will most likely be one of them.

There are three versions of the interface SATA. They differ in data transfer speed. SATA, SATA II and SATA III at speeds of 1.5, 3 and 6 gigabytes per second, respectively. All interface versions SATA look the same and are compatible with each other. You can connect them in any combination, as a result, the data transfer rate will be limited to the slower version. At the same time, the speed of the hard drive is even slower. Therefore, the potential fast interfaces will be able to open up only with the advent of new high-speed drives.

If you decide to purchase an additional SATA hard drive, check if you have an interface cable as shown in the picture. It is not sold with a CD. (They usually come with motherboard.) Also, among the power supply connectors, there should be at least one free one for connecting a hard drive, or you may need an adapter from the old standard to the new one.

Now about the hard drive itself: The main parameter is, of course, the capacity. As I mentioned above, please note that it will be slightly less than stated. For operating system and programs require 100 - 200 gigabytes, which is quite a bit by modern standards. how much you might need extra space you can determine by experience. Large volumes may be required, for example, to record high quality video. Modern films in HD format reach several tens of gigabytes.

In addition, among the main parameters indicate:

1. Form Factor- disk size. 1.8" and 2.5" disks are used in . For a desktop computer, you should purchase a 3.5-inch drive. They have the same SATA connectors and a laptop drive can work in desktop computer. But small drives are made with an emphasis on compactness and low power consumption, and in terms of performance they are inferior to larger models. And they cost more.
2. RPM- disk rotation speed. Measured in revolutions per minute ( RPM- short for revolutions per minute). The faster the rotation speed, the faster the disk writes and reads information. But it also consumes more energy. Today, the most common discs with 5400RPM and 7200RPM. Lower RPMs are more common in laptop drives, drives large capacity(more than two terabytes) and the so-called "green" drives, so named because of the reduced power consumption. There are also hard drives with a rotational speed 10000RPM and 15000RPM. They are designed to work in highly loaded servers and have an increased reliability resource, but they also cost much more than conventional ones.
3. Manufacturer. On the this moment there are several large manufacturers in the storage market. Among them there is quite tough competition, so they are in no way inferior to each other in quality. Therefore, you can choose any of the well-known names: Hitachi, HP, Seagate, Silicon power, Toshiba Transcend, western digital.

Today we will talk about what HDD drives are, what they are, and consider their characteristics. We will find out which of them are the best, and which HDDs are not worth buying.

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, reading heads, spindle (motor), and control board. The spindle, on which the magnetic plates are fixed, spins them up to several thousand revolutions. in a minute. It is believed that the higher the torque of the spindle, then the speed of its reading is greater. Although important factors include: random access and recording density. HDD differ among themselves in speed, volume, and of course reliability. This parameter is guaranteed by the manufacturer.

What are the best manufacturing companies?

Samsung drives are considered the most reliable and fastest. Hitachi also produces very good rims but they are slower. Western Digital's HDDs are of average quality. It turned out that this company initially began to produce its products at cheap factories that did not have high-quality equipment. by the most poor quality production of devices of this type from famous brands is the once leading US electronics firm Seagate. Well, Fujitsu and Toshiba now cannot boast of the quality of hard disk production at all.

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.
The speed of the hard drive of the computer's system unit is more than 7000 rpm, but HDDs with a performance of no more than 5500 rpm come across on sale. Such low-speed copies are not worth buying. But laptop drives with a rotation speed of 5400 rpm. They are much quieter and don't get as hot.

A hard disk buffer is called cache memory, and serves to speed it up. It ranges from 32 to 128 MB. Although 32 MB. will be enough for him normal operation. The read and write speed is one of the most important parameters that greatly affects the working performance of the device.

Information exchange rate

A good indicator for HDD is considered to be a read speed of 110 - 140 MB / s. You should not buy an HDD with a speed not exceeding 100 Mb / s. Random access time is second important indicator 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 affect the operation of drives and their speed in any way. Over the past ten years, hard drives have not changed at all. Therefore, the price for them remained approximately at the same level.

WindowsTune.ru

What is an HDD in a computer?

In various programs that monitor computer performance, you can find such a designation as HDD. On the cases of most computers 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 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 - this is if the light does not light 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 disk will decrease, and the performance of running programs will increase.

AskPoint.org

hdd what is it?

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

Previously, all information on computers, which at that time were called computers, was stored on devices called punch tapes. What is perforated tape? In fact, this is a piece of paper made of cardboard, in which special holes are made. But this " stone Age» computers. The next step in the development of personal computers was a technology called magnetic recording. It is this principle that underlies the technology of functioning 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 amount of stored information is one of the main achievements of today's HDDs.

Why and what is the HDD for?

Why is a hard disk (HDD) needed and how is it used directly by the computer's operating system itself? As a rule, any computer stores this or that information in itself, and the hard disk is the very device on which information is stored. Today it is very important function for any computer (storage of information on digital media), because without a hard drive, we, personal computer users, would have to have constant access to the Internet or local network, and computers without such capabilities would lose a significant portion of their functionality.

In more "scientific" terms, a hard drive is the storage component of any PC. The main task of this component is to store information for a long time. The hard drive, unlike the "RAM" of the computer (RAM), is not a memory called volatile. What does it mean? Let's imagine that you worked on a computer with a document, saved it, and then, of course, turned off the computer. If the HDD memory were volatile, then all the information you saved would be irretrievably lost. Why? The thing is that for the normal operation of volatile memory, a constantly on power supply is required. It is on this principle that the RAM of a computer works, but the memory on hard drives does not, since it is not volatile. For the same reason, this type of memory is the best for storing any information, whether it be documents, photos, videos, etc. By the way, the operating system, as a rule, is installed on the hard drive in a section specially designed for this. Of course, all of the above does not mean at all that information has been stored on this type of device for decades, on the contrary, it needs to be “cleaned” periodically, that is, unnecessary and unnecessary information must be deleted.

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

What does HDD mean? The answer sounds like this: HDD is a hard disk drive that uses magnetic principle work. Abbreviation with in English(hard disk drive) translates as a hard disk. The word magnetic can also be added to this abbreviation, which means magnetic.

By the way, why is it 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 solid, in fact, this is the explanation of this name. Is it possible to say a few words about floppy disks that 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 Winchester, everything is somewhat more complicated here. 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 30 MB modules). This designation echoed the name of the 30-30 Winchester cartridges. Everything is simple.

What do these devices look like inside a personal computer?

Now the most popular models HDDs are either 2.5 or 3.5 inches. The latter are used in conventional PCs, and the 2.5-inch form factor is designed for laptops and portable versions of devices.

The first thing to say is that in the world computer technology everything is improving, and fast enough, and the situation with our type of devices is no exception. What does a hard drive look like on a computer today? Now the most popular HDD models are 2.5 or 3.5 inches. The latter are used in conventional PCs, and the 2.5-inch form factor is designed for laptops and portable versions of devices. In older PCs, you can also find disks with other sizes, but they are obsolete and are not usually used in modern computers. What sizes are out of date? By and large - all but the above. Previously, HDDs had a format of 8 and 5.25 inches.

The amount of memory of modern hard drives.

For most users, the memory size looks like key indicator in choosing the most suitable model for use. Speaking about computers in Russian, you can say directly - no one cares about anything specifications(noise, speed) except for one. As you may have guessed, this is exactly the amount of information that can fit on the disk. It doesn't matter that the hard drive can be noisy and slow, the main thing is how much it "fits" on it. This is what the vast majority of users care about. Moreover, many other characteristics in the eyes of ordinary people do not look so significant, but the number free space is 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, you should remember one trick of manufacturers. When specifying the amount of device memory, they round all values, so real volume memory will be slightly less than indicated on the package. The thing is that manufacturers round off the indicators in such a way that there are 1000 bytes in one kilobyte, not 1024. Hence the “error”. Is it possible to deal with this somehow? 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 to a smaller amount of real hard disk memory instead of the declared one. How about saving money? Buy yourself a cookie

A hard drive, hard drive or just a screw, hard disk, hdd (Hard Disk Drive) - this storage device has several names, it 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, movies are recorded, and the operating system of the computer itself is recorded on it. Nowadays, SSD drives are becoming more and more popular. hybrid drives SSHD, we will talk about them and their pros and cons in a separate article.

What are the disks?

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

Form factor (size)

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

For stationary home computer standard size 3.5-inch, in modern cases there are 2.5-inch drive bays, they are mainly designed for SSD installations drive, put in a computer instead of a 3.5-inch drive, 2.5-inch drives don't make much sense, only in very compact cases, such as micro-ATX.

In laptops, on the contrary, space saving is very relevant and 2.5-inch form-facts are used for them. There are smaller drives - 1.8 inches, 1.3 inches, 0.8 inches, but in modern devices you will not find them anymore.

Capacity (Why is the capacity of the drive smaller than advertised?)

A parameter that directly affects 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, and computers calculate differently 1 KB = 1024 bytes, hence the confusion arises for users who encounter this for the first time and the larger the volume, the more difference obtained 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 with films.

Interface

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

ATA aka PATA (IDE)

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

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

SCSI and SAS

SAS drives are used in server hardware. Replaced the SCSI interface. Regular user you should know, only that they are designed for completely different tasks and are not used in home PCs.

Spindle speed

The number of revolutions of the spindle (the axis on which the plate or several plates rotate inside the disk). There are several standards, in home computers and laptops drives with a rotation speed 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 a few more parameters such as noise level, MTBF, etc. v 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 desktop)

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

Iwhat is internal hdd

Hard Disk Drive, abbreviated hdd, one of the most important, most expensive and most complex components modern computer. HDD is designed for long-term storage of large amounts of information that the PC uses, operating system files and programs. It is from the hard drive, or as computer scientists call it “screw”, that the operating system is loaded. If the drive fails, you have to spend a lot of money to buy a new hard drive. But most importantly, all information will be lost if a backup copy has not been created in advance.

Hard drives are:
- external - External HDD;
- internal - Internal HDD.

Features of choosing internal hdd.

Inside the case of the system unit is internal hdd what it is and what to look for when buying. Hard drives are designed to store information and boot the operating system. Hard drives, which ensure reliable and efficient operation of the operating system, are subject to increased requirements. For internal hdd, whose main task is to store and process information, the requirements are completely different.
The problem of choice is solved by the ability to install several hard drives in modern PCs, each of which performs its own tasks.

Internal internal hdd are available for personal computer and laptop. They differ in size:
- 3.55 inches for PC;
- 2.5 inches - for a laptop.

Hard drive settings.

The need to purchase a new device arises in two cases: there is not enough capacity of a working hard drive for the normal operation of the computer, or the old disk has failed.
Winchester is one of the most unreliable PC components, as it combines a complex mechanical part and electronic boards. In addition, mechanics cannot stand physical impact: vibration, shaking, shock. How to find out that the hard drive is not in order? If there are problems with the device, the computer may restart at any time, freeze during operation, or turn off.
What is better to do: buy new hard drive or repair the old one? The answer is clear: it's easier and cheaper to buy a new internal hdd. These devices are rarely repaired.

When choosing a hard drive, there are three main parameters to consider:

1. Interface type.
Your drive must be fully compatible with motherboard. There is different variants interfaces: SCSI, SATA, IDE and SAS. IDE connection is only suitable for older computers. Currently, the most commonly used different versions SATA. Modern interfaces to connect drives allow you to work with files much faster.

2. Performance.
The speed of the disk is affected by the speed of rotation of the spindle. There are standard rotation speeds: from 5400 to 7200 rpm. How to make the right choice? 5400 rpm is enough for data storage, if you need to install systems and programs, you must select a screw with parameters of -7200 rpm. "Green" drives with 5400 revolutions per minute are characterized by low energy consumption and quiet operation. More revolutions provide more read and write speed.
There are models that have speeds from 10,000 to 15,000 rpm. Used exclusively for servers and for professional purposes.

The intermediate memory buffer - cache, also affects the performance of the internal hdd. Cache values ​​range from 8 to 64 MB. How larger size cache - the faster the screw:
- 8 MB is enough for 500 - 750 GB;
- 16 MB - for 1 TB.

3. Capacity.
HDD capacity is measured by the amount of information volume that fits on the device. The first internal hdd had a capacity of only 60 MB. The smallest capacity of hard drives today is 160 GB. Modern devices most often have ranges of values ​​​​from 200 to 500 GB. The size of some devices can reach up to 3 TB.
When choosing, be guided by your needs and financial capabilities: the higher the capacity, the more information will fit, but the price will also increase significantly.

The last two parameters are quite difficult to combine on one device. Therefore, conventionally, disks are divided into:
- universal;
- capacious;
- fast.

When choosing internal hdd, you need to decide on functional tasks. If the computer has one hard drive, then it is better to choose universal models that are made with optimal ratio speed and capacity. A fast hard drive is used as system disk. To store a large amount of information, capacious disks are chosen. If the choice is made correctly, the whole system will work balanced and without failures.

Advantages and disadvantages of different types of internal hdd.

Universal ones have a sufficiently high degree of reliability, and do not have serious shortcomings. Fast hard drives, in addition to speed, are also highly reliable. The disadvantages include rapid heating and noise.
Capacious internal hdd are considered the most unreliable. Especially models whose capacity exceeds 1 TB. The advantages of such hard drives are reduced noise, low power consumption and moderate heating.

Features of choosing hdd for a laptop.

Laptops do not need fast or capacious internal hdd. It is best to choose a universal hard drive with balanced characteristics.

The main differences between internal hdd for a laptop:
1. Devices have smaller sizes and more compact.
2. Hard drives are installed with a spindle speed of 4200 to 5400 rpm, which ensures low power consumption.
3. HDD capacity in laptops is not more than 200 GB.

Like in a laptop

You can replace the hard drive in a laptop yourself. Usually this does not cause any difficulties. The main condition is caution. In all laptops, the internal hdd is located in a metal frame inside the case. The new hard drive is inserted into the same frame.
A prerequisite for replacement is to check the compatibility of the new internal device with the laptop motherboard. If a newly purchased hard drive has an inappropriate connector, then it will not be possible to install it. Therefore, before buying, read the instructions, check technical specifications, define the interface type. Most often for hdd connections are used SATA interfaces and IDE, differing in the width of the cable and connector.

Currently, internal hdd, which are installed in laptops, practically do not lose in terms of performance and speed. hard drives in PC. Moreover, the speed of access to information can always be increased by connecting an additional external drive.

Manufacturers.

Today, there are five main brands in the lead: Seagate, Western Digital, Toshiba, Hitachi, Samsung. There are, of course, other models trademarks. But, as a rule, these are licensed "repetitions" of already well-known models.
Define best brand it is not at all easy, as well as to say which hard drive will last longer. Basically, all drives are quite reliable and have almost the same characteristics. But the most reliable firms are still considered Seagate and Western Digital.

Do right choice reviews on various forums will help. Type in the brand of the drive in the search engine and read customer reviews. Do not trust one site or forum. Use multiple sources to avoid wasting money and losing valuable information. Choose wisely. It is important to remember: you need to purchase hard drives only from a trusted seller, and not at the market.

Hard drives, or, as they are also called, hard drives, are one of the most important components computer system. Everyone knows about it. But far from everyone modern user even in principle guesses how the 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, 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, it is true. Do not forget that on the hard disk, 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 some marks by which you can quickly find necessary information.

Modern models are quite diverse: ordinary HDDs, external rigid disks, high-speed solid-state drives SSD, although they are not specifically referred to as hard drives. Further, it is proposed to consider the device and the principle of operation of the hard disk, if not in in full, then, by 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 modern HDD 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 thinking about why they call hard drives related to small arms. It would seem that what can 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 consonant with the brand of the popular at that time gun "30-30 Winchester". True, in the early 90s in America and Europe this name practically fell into disuse, but it still remains popular in the post-Soviet space.

The device and principle of operation of the hard drive

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

The hard drive itself is a set of platters, the number of which can vary from four to nine, interconnected by a shaft (axis) called a spindle. The plates are placed one above the other. Most often, the material for their manufacture is 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 are responsible for writing and reading information (one for each plate), 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.

At the same time, the basic principle of the computer hard drive is that information is not recorded anywhere, but in strictly defined locations, called sectors, which are located on concentric tracks or tracks. To avoid confusion, uniform rules apply. It means that the principles of operation of drives on hard drives, in terms of their logical structure, are universal. So, for example, the size of one sector, taken as single standard worldwide is 512 bytes. In turn, sectors are divided into clusters, which are sequences of adjacent sectors. And the peculiarities of the principle of operation of a hard disk in this regard are that the exchange of information is carried out by whole clusters (an integer number of chains of sectors).

But how is information read? Principles of hard drive operation magnetic disks look like this: using a special bracket, the reading head moves in the radial (spiral) direction to the desired track and, when rotated, is positioned above the 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 called cylinders.

At the same time, one more principle of hard disk operation can be distinguished: the closer the read 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 physics of magnetism, formulated by Faraday and Maxwell.

As already mentioned, plates made of non-magnetically sensitive material are coated with a magnetic coating, the thickness of which is only a few micrometers. In the process of work, a magnetic field arises, which has the so-called domain structure.

The 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 an external magnetic field, the disk's own field begins to orient itself strictly along the magnetic lines, and when the impact stops, zones of residual magnetization appear on the disks, in which the information that was previously contained in the main field is stored.

For creating external field when writing, the reading head responds, and when reading, the zone of residual magnetization, being opposite the head, creates an electromotive force or EMF. Further, everything is simple: the change in the 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 for computer science reasons, can be associated as a certain dotted sequence of bits of information. But, since the location of such points is absolutely impossible to calculate exactly, you need to install some pre-provided marks on the disk that helped determine the desired location. The creation of such marks is called formatting (roughly speaking, breaking the disk into tracks and sectors combined into clusters).

The logical structure and principle of operation of the hard disk 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 way to bring the hard drive into working condition do not have to speak. How to initialize a new hard drive will be discussed separately.

Low-level formatting involves a 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 disk 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 plate. Thus, when organizing direct access the same RAM accesses directly to a given address, and does not search for the necessary information over the entire surface, due to which speed is achieved (although this is not the most important thing). Please note that when executing low-level formatting absolutely all information is erased, and in most cases it cannot be restored.

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

Logical formatting primarily affects the system area, which consists of boot sector and partition tables (Boot record), file allocation tables (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, in the event of errors and failures, is not subject to change or deletion.

HDD Main Features

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

The principle of operation of the hard drive and the 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);
• speed (data access speed, reading and writing information);
• interface (connection method, controller type).

Capacity is the total amount of information that can be written and stored on a hard drive. The HDD industry is developing so fast that today hard drives with volumes of the order of 2 TB and above have already come into use. And, as it is believed, this is not the limit.

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

Drives with an IDE interface are not expensive, but among the main disadvantages are limited quantity simultaneously connected devices (maximum four) and a low data transfer rate (even if Ultra DMA direct memory access or Ultra ATA protocols (Mode 2 and Mode 4) are supported. Although, as it is believed, their use allows you to increase the read / write speed up to 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 with the motherboard.

Speaking about what is the principle of operation of a hard drive and characteristics, one cannot ignore and which is the successor to the IDE ATA version. The advantage of this technology is that the read/write speed can be increased up to 100 Mb/s by using the high-speed Fireware IEEE-1394 bus.

Finally, the SCSI interface is the most flexible and fastest compared to the previous two (write/read speed reaches 160 Mb/s and more). But these hard drives are almost twice as expensive. But the number of simultaneously connected storage devices is from seven to fifteen, the connection can be made without de-energizing the computer, and the cable length can be about 15-30 meters. Actually, this HDD type mostly used not in user PCs, but on servers.

Speed, which characterizes the speed of transmission and throughput I/O, usually expressed in terms of transfer time and amount of sequential data transferred, and is expressed in Mbps.

Some additional options

Speaking about what is the principle of operation of a hard drive and what parameters affect its operation, one cannot ignore some additional characteristics that may affect the performance or even the life of the device.

Here in the first place is the rotation speed, which directly affects the search and initialization (recognition) time of the desired sector. This so-called hidden time search - the interval during which the desired sector turns to the reading head. Today, several standards have been adopted for spindle speed expressed in revolutions per minute with dwell times 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 it takes to search for sectors, and in physical terms - to rotate the disk before setting for the head desired point plate positioning.

Another option is internal speed transmission. On the outer tracks it is minimal, but increases with a gradual transition to the inner 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 faster read speed. The external speed has fixed values ​​and directly depends on the interface used.

Finally, one of important points associated with the presence of a hard drive its own cache or buffer. In fact, the principle of the hard disk in terms of buffer use is somewhat similar to the operational or virtual memory. The larger the amount of cache memory (128-256 KB), the faster the hard drive will work.

Main requirements for HDD

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

The main standard for most HDDs is considered to be 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.

In terms of reliability, the S.M.A.R.T. self-test function is responsible for this, which monitors the status individual elements hard disk by constantly monitoring. On the basis of the collected data, even a certain forecast of the appearance of possible malfunctions in the future can be formed.

It goes without saying that the user should not be left out. So, for example, when working with the HDD, it is extremely important to observe the optimal temperature regime(0 - 50 ± 10 degrees Celsius), avoid shocks, bumps and falls of the hard drive, dust or other small particles getting into it, etc. By the way, many will be interested to know that the same particles of tobacco smoke are about twice more distance between the reading head and the magnetic surface of the hard drive, and a human hair - 5-10 times.

Initialization issues in the system when replacing a hard drive

Now a few words about what actions should 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 dwell 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, in the disk administration section, initialize and create boot record, create a simple volume, assign an identifier (letter) to it, and format it with a choice of file system. Only after that the new "screw" will be completely ready for work.

Conclusion

That, in fact, is all that briefly concerns the basics of the functioning and characteristics of modern hard drives. The principle of operation of an external hard drive was not considered fundamentally here, since it is practically no different from what is used for stationary HDDs. The only difference is only in the method of connecting an additional drive to a computer or laptop. The most common is the connection 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 in blue color), of course, provided that the external HDD supports him.

For the rest, it seems that many have at least a little understood how a hard drive of any type functions. Perhaps too many topics have been cited above, even from school course physicists, however, without this, to fully understand all the basic principles and methods inherent in the technologies of production and HDD applications, cannot be understood.