Every computer has a hard drive or, as it is often called, a hard drive, which is the main place to store all the information used by the computer and its user. The hard disk stores the installed operating system, all programs used by the user, and data. The processor takes the information necessary for processing from the hard drive and then writes it back to the media. The amount of information that is stored on a hard drive depends on its size.
The very first hard drive models allowed storing up to 10 MB of data on their disks, which was a lot in those days. Now modern media allow you to store thousands and tens of thousands of megabytes. The amount of memory on modern models is calculated in gigabytes and terabytes. This makes it possible to store a huge amount of movies, music, video clips, games and other data. A significant increase in the amount of memory on the HDD is associated with the progressive development of computer technology, as a result of which movies, games and other data take up more and more free space.
Design features of hard drives
A modern hard drive consists of several metal disks on which information is recorded. Discs are covered with iron oxide or other special compound capable of storing the effects of a magnetic field. The number of discs depends on the volume of the media and is usually in the range from 1 to 3. Metal discs are perfectly even, smooth and balanced, so they can rotate at high speed, according to the standard it can be 5400, 7200 or 10000 rpm.
Special heads move along the discs with the highest positioning accuracy. Each disk has 2 magnetic heads. Reading data from the surface of the disks is carried out using the installation of special magnetoresistive heads, they work depending on how the magnetic field changes on the surface of the disk. Data is transmitted to a computer as a result of receiving an analog signal that turns into a digital form.
On discs, information is stored in tracks arranged around a circle. To work with the data on the media, the magnetic heads move along the tracks. The movement of the heads is carried out thanks to the use of a special solenoid drive. Such heads can access any location on the disc due to their high rotational speed. The heads are located on both sides of the disks, so each of them performs work on one side and is completely responsible for it.
A sector on a hard drive allows you to store 512 bytes of information, and each track of a hard drive consists of many sectors. The maximum amount of information that can be stored on a hard drive depends on the number of sectors, heads and cylinders. The number of HDDs may be the same, but their memory capacities will be completely different. This is due to the fact that in order to increase the volume, it is more convenient to increase the density of sectors on each of the disks than to increase their number, which will lead to a significant increase in the size of the media. The development of computer technology leads to the fact that each PC component becomes smaller in external dimensions, and the possibilities, on the contrary, increase.
There are such concepts as physical disk placement and logical. The physical is how the storage medium is arranged inside, and the logical is how the computer sees it. In reality, the physical and the logical are completely different. If physically, for example, 3 disks can be installed inside the hard drive, then logically there can be any number and any size, one logical disk can be the size of two or more physical ones and vice versa.
In the production of hard drives, it is almost impossible to avoid damage to sectors or tracks, but they are not used and are not taken into account by the media due to the marks.
Hard drives are designed for use in home PCs, and are for use in servers. The latter are subject to much greater requirements, because they work with a significant load and must provide high performance and speed.
Hard drive characteristics
In order to choose the right hard drive suitable for certain purposes, it is necessary to understand a large number of characteristics. The first thing you should pay attention to is the form factor. 3.5-inch hard drives are installed on stationary PCs, and 2.5-inch hard drives on laptops. There are also other less common form factors. The second important parameter is the interface through which the device connects to the computer. The PC uses various variations of the SATA interface.
One of the important parameters is the capacity, which determines the amount of data stored on the device. The speed of rotation of the shaft on which the disks are located affects the speed of working with information.
When choosing a hard drive, you should pay attention to the buffer size, which directly affects the speed of the device with information.
Each hard drive makes noise during operation, like any other mechanical device. During operation, noise can cause significant inconvenience, so you need to pay attention to its level when choosing a model suitable for your PC.
If the device is planned to be frequently transferred from one computer to another, then such a parameter as shock resistance is important. The higher it is, the less likely it is to lose information upon impact or damage the hard drive.
While working with information, the disk gives the requested information at a certain speed. This indicator is called "Random Access Time" and the smaller it is, the faster the request will be transmitted.
Having an idea about all the parameters, characteristics and design of modern hard drives, you can quickly choose the right hard drive to perform the tasks on your PC.
We, users of a personal computer, often come across the abbreviation HDD. And the desire to find out what an HDD is, where it is and what it is for is justified.
HDD stands for "hard disk drive". Simply put, it's a hard drive. Gradually fading into the past, they are being replaced by SSDs, but they will occupy their niche in the HDD market for a long time to come.
Why is the drive "hard"
HDD in the computer as soon as they are not called. Hard drive, hard drive, hard drive, screw - just a small list of his names. Why all the same "hard disk drive"?
Unlike "floppy" disks (floppies), HDD data is written to hard platters, which, in turn, are covered with a layer of ferromagnetic material. They are called nothing more than "magnetic disks". A hard drive uses one or more platters on the same axis. Readers (heads) do not touch the surface of the plates during operation. This is explained simply: with the rapid rotation of the plates, a layer of oncoming air flow is formed. The distance between the reader and the work surface is very small - only a few nanometers, and the air layer, which excludes mechanical contact, ensures a long service life. If the plates do not rotate at the proper speed, then the heads are in the so-called "parking" zone - outside the boundaries of the plates.
A distinctive feature of the HDD in a computer is that the storage medium is combined with the drive, as well as with the necessary electronics unit in one housing.
HDD Main Features
Like any technical device, a hard drive has a number of characteristics, based on which, we can draw conclusions about its relevance.
- Capacity is one of the most significant quantities. Specifies the amount of data that the drive can store.
- Dimensions (form factor). The most common variations are 3.5 and 2.5 inches. Specifies the width of the device.
- The speed of rotation of the axis, spindle. The number of revolutions per minute. The parameter significantly affects the speed of access to data and directly on the speed of their transfer. The most common options: 4200, 5400, 7200, 10,000 rpm.
- The number of I/O operations per second. For modern disks, this number approaches 50 (with random access to data), with sequential access, respectively, higher - about 100.
- Power consumption is an important parameter for portable devices (we are talking about laptops / netbooks).
- Buffer size. Buffer - intermediate memory. Its purpose is to smooth out read/write speed differences. In modern HDDs, it is usually located in the range from 8 to 64 megabytes.
I hope we were able to figure out what an HDD is in a computer, and even expand our horizons a little in the world of computer hardware.
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 is 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 time 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 discs, 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. The lowest quality of the production of devices of this type from well-known brands is the once leading American electronics company 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 its 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 the second most important indicator of hard drive performance, after reading and writing. It is believed that the smaller this parameter, the better the quality of the device. 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 is the "stone age" of 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, this is a very important function for any computer (storing information on a digital medium), because without a hard drive, we, users of personal computers, would have to have constant access to the Internet or a 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 the magnetic principle of operation. The abbreviation from English (hard disk drive) is translated 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 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.
The first thing to say is that in the world of computer technology everything is improving, and quite quickly, 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, memory size seems to be a key indicator in choosing the most suitable model for use. Speaking about computers in Russian, one can say bluntly - no one cares about all the technical characteristics (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 the inhabitants do not look so significant, but the amount of 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. Indicating the amount of memory of the device, they round all the values, so the actual amount of memory will be slightly less than indicated on the packaging. 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
Many of you know that all the information on the computer, presented in the form of files and folders, is stored on the hard drive. But, what is a hard drive and what it is intended for, not many will correctly answer. It is very difficult for people who are far from programming to imagine how information can be stored on some kind of piece of iron. After all, this is not a box or a piece of paper on which this very information can be written down and hidden in a box. Yes, a hard drive is not a box with a letter.
A hard disk (HDD, HMDD-from the English hard (magnetic) disk drive) is a magnetic storage medium. In computer slang, it is called "Winchester". It is designed to store information in the form of photos, pictures, letters, books in various formats, music, movies, etc. Outwardly, this device does not look like a disk at all. Rather, it looks like a small rectangular iron box.
The internals of a hard drive are like an old turntable.
Inside this metal box, there are round aluminum or glass disc plates located on the same axis along which the reading head moves. Unlike a player, the hard disk head does not touch the surface of the platters during operation.
For convenience, the hard disk is divided into several sections. This division is conditional. This is done using the operating system or special programs. The new partitions are called logical drives. They are assigned the letters C, D, E or F. It is usually installed on the C drive, and the files and folders are stored on other drives so that your files and folders do not suffer if the system crashes.
Watch a video about what a hard drive is:
Key Features of Hard Drives
- Form factor is the width of the hard drive in inches. The standard size for a desktop computer is 3.5 inches, and for laptops 2.5 inches;
- Interface- Modern computers use various versions of SATA connections to the motherboard. SATA, SATA II, SATA III. Older computers use the IDE interface.
- Capacity- this is the maximum amount of information that a hard drive can store, measured in gigabytes;
- Spindle speed is the number of spindle revolutions per minute. The faster the disk spins, the better. For operating systems, you need to install drives of 7200 rpm and higher, and for file storage, you can install drives with a lower speed.
- MTBF is the mean time between failures as calculated by the manufacturer. The larger it is, the better;
- Random access time- this is the average value of the time required for the head to position on an arbitrary section of the plate. The value is not constant.
- impact resistance is the ability of a hard drive to withstand pressure changes and shocks.
- Noise level, which the disc emits during operation is measured in decibels. The smaller it is, the better.
Now there are already SSD drives (solid-state drive in simple translation - solid-state drive), which have neither a spindle nor platters. This is a storage device based on memory chips.
SSD drives are perfectly quiet and have very good read and write speeds. But they are still very expensive and not very reliable, so they are installed only under operating systems, and IDE and SATA hard drives are used to store files.
Hard disk or HDD This is a device that allows you to store information for a long time and which is non-volatile. In simple words, an iron box where all your documents, movies, operating system and everything else are located. If we draw a life analogy, then this is something like a big album. Taking a pencil in hand, you can draw or write essays. If you don't like something, you can always take the "eraser". The bottom line is that while the album is on the shelf, all the data remains intact.
There are two important aspects in this case. The first is long-term storage. The second is energy independence. If in the first case everything should be clear from the album example, then for the second case I will give some explanations. The bottom line is that the hard drive does not require power to store information, unlike RAM. So you can turn off your computer from the network and know that the data will be safe.
Note: There is a common version of where the slang names of this box came from. Today, a hard drive is often referred to as a hard drive or, for short, a screw. It came from the fact that the first such device had a code similar to Winchester rifle cartridges. It is hard to say how true this is, but the version is considered the most real.
Let's take a closer look at this box.
If you notice, then I have already mentioned the abbreviation HDD several times and for a reason. The fact is that the technical name of this box is a hard disk drive or hard (magnetic) disk drive.
But, back to the hard drive device. This box is based on the technology of magnetic recording of information. And here's how it works. There are round hard drives (they are also often called pancakes) covered with a ferromagnetic material (it can change its magnetic properties). There is a special moving head (consists of two parts), which, in fact, reads and writes data (part of the head for reading, part for writing).
The process itself is as follows. The disk is constantly spinning at a fairly high speed, and the head walks along the disk and either reads data or writes at the right time. It is important to note that the head does not touch the disk, otherwise the disk coating could be damaged. When the disk is turned off, the head is in a special zone (parking), again to protect the ferromagnetic coating from damage.
It is worth knowing that the internal mechanism is designed in such a way that it would be physically very difficult to damage the surface of the data disc. However, over time, parts of the ferromagnetic surface may become unusable. Here, as in the well-known expression - "Nothing lasts forever."
It is also worth knowing that there may be several such plates inside the hard drive box. As you may have guessed, the number of pancakes affects the amount of information stored. But, it is not limited to this. For example, a long time ago, disks were 1.5 times larger than today's, and 20-40MB were placed on them.
Figure 1 Simplified Diagram of a Round Hard Drive
Note: In the figure, the numbers indicate: 1 - geometric sector, 2 - track sector, 3 - track, 4 - cluster.
Consider, in a little more detail, the very surface of the pancakes. So that the storage and recording of information can be structured, the entire surface is divided into special tracks. Then the entire disk is divided into geometric sectors (equal to each other). The part of the track that is inside this geometric object is called the track sector or simply sectors. The combination of several sectors is called a cluster.
Since the disks spin at a fairly high speed (for example, 7200 rpm), it is the cluster that is used as the minimum storage unit. Typically, a cluster is represented by a size of 4 KB and consists of 8 sectors of 512 bytes. By the way, this is why the real size of a text file consisting of only one character will be 4 KB, since, in principle, the size is divided precisely into clusters.
Note: It is worth knowing that there are methods that allow you to store data of several files in one cluster, but usually the division goes exactly by clusters.
Note: I also advise you to read the article Solid state hard drive or SSD drive, as this is the next round of data storage devices.
Hard drive specifications
If with a hard drive device, I hope it became clear to you, then for the sake of completeness, it remains to consider the issue of the main characteristics of the HDD.
1. Form factor. The words are terrible, but in fact they mean only the physical size of the disk. For desktop computers, it is usually 3.5 inches, for laptops it is less, only 2.5 inches.
2. Capacity. This is essentially the size of how much data a hard drive can store. Today, disks are measured in gigabytes and terabytes.
3. Spindle speed. This is exactly the same speed with which pancakes are spinning. Usually it is 5400 for laptops and 7200 for regular computers. There are other speeds, but they are simply not needed for home use.
4. Noise level. Here, probably, you can guess what is at stake. There are very loud hard drives, usually the simplest ones, and there are also quieter ones.
5. Shock resistance or in the common people survivability. In fact, it indicates what kind of overloads the hard drive can endure without damaging data. However, I strongly advise you not to check this characteristic.
6. Access interface. The interface defines the connectors that are used to connect drives to the computer. Previously, almost all HDDs for home computers were IDE, but today we are mainly talking about SATA. In the case of external drives, usually USB. It is worth knowing that in reality the connector of the disk itself is not USB, just an adapter with a controller is used inside the box.
