Hard drive - what is it? Features of hard drives. What is a hard drive and why is it needed What is a hard drive

During computer startup, a set of firmware stored in the BIOS chip checks the hardware. If everything is in order, it transfers control to the operating system loader. Then the OS loads and you start using the computer. At the same time, where was the operating system stored before turning on the computer? How did your essay that you wrote all night stay intact after turning off the power of the PC? Again, where is it kept?

Okay, maybe I've gone too far and you all know very well that computer data is stored on a hard drive. Nevertheless, not everyone knows what it is and how it works, and since you are here, we conclude that we would like to know. Well, let's find out!

By tradition, let's look at the definition of a hard drive on Wikipedia:

HDD (screw, hard drive, hard disk drive, HDD, HDD, HMDD) is a random access storage device based on the principle of magnetic recording.

They are used in the vast majority of computers, as well as separately connected devices for storing backup copies of data, as file storage, etc.

Let's figure it out a little. I like the term hard disk drive ". These five words convey the whole point. HDD is a device whose purpose is to store data recorded on it for a long time. HDDs are based on hard (aluminum) disks with a special coating, on which information is recorded using special heads.

I will not consider in detail the recording process itself - in fact, this is the physics of the last grades of the school, and I am sure you have no desire to delve into this, and the article is not about that at all.

Also note the phrase: random access ” which, roughly speaking, means that we (computer) can read information from any section of the railway at any time.

It is important that the HDD memory is not volatile, that is, it does not matter whether the power is connected or not, the information recorded on the device will not disappear anywhere. This is an important difference between a computer's permanent memory and temporary ().

Looking at a computer hard drive in real life, you will not see any disks or heads, since all this is hidden in a sealed enclosure (hermetic zone). Externally, the hard drive looks like this:

Why does a computer need a hard drive?

Consider what an HDD is in a computer, that is, what role it plays in a PC. It is clear that it stores data, but how and what. Here we highlight the following functions of HDD:

• Storage of OS, user software and their settings;
• Storage of user files: music, video, images, documents, etc.;
• Using part of the hard disk space to store data that does not fit in RAM (paging file) or storing the contents of RAM while using sleep mode;

As you can see, a computer hard drive is not just a dump of photos, music and videos. It stores the entire operating system, and in addition, the hard drive helps to cope with the workload of RAM, taking on some of its functions.

What is a hard drive made of?

We partially mentioned the components of the hard drive, now we will deal with this in more detail. So, the main components of the HDD:

• Frame Protects hard drive mechanisms from dust and moisture. As a rule, it is airtight so that the same moisture and dust do not get inside;
• Disks (pancakes) - plates made of a certain metal alloy, coated on both sides, on which data is recorded. The number of plates can be different - from one (in budget options) to several;
• Engine - on the spindle of which pancakes are fixed;
• Head block - a design of interconnected levers (rocker arms), and heads. The part of a hard drive that reads and writes information to it. For one pancake, a pair of heads is used, since both the upper and lower parts of it are working;
• Positioning device (actuator ) - a mechanism that drives the block of heads. Consists of a pair of permanent neodymium magnets and a coil located at the end of the head unit;
• Controller - an electronic microcircuit that controls the operation of the HDD;
• parking zone - a place inside the hard drive next to the disks or on their inside, where the heads are lowered (parked) during downtime, so as not to damage the working surface of the pancakes.

Such a simple hard drive device. It was formed many years ago, and no fundamental changes have been made to it for a long time. And we move on.

How a hard drive works

After power is supplied to the HDD, the engine, on the spindle of which the pancakes are fixed, begins to spin up. Having gained a speed at which a constant stream of air is formed near the surface of the discs, the heads begin to move.

This sequence (first the discs spin up, and then the heads start working) is necessary so that the heads hover over the plates due to the resulting air flow. Yes, they never touch the surface of the disks, otherwise the latter would be instantly damaged. However, the distance from the surface of the magnetic platters to the heads is so small (~10 nm) that you cannot see it with the naked eye.

After starting, first of all, service information about the state of the hard disk and other necessary information about it, located on the so-called zero track, is read. Only then does the work with the data begin.

Information on the computer's hard drive is recorded on tracks, which, in turn, are divided into sectors (such a pizza cut into pieces). To write files, several sectors are combined into a cluster, which is the smallest place where a file can be written.

In addition to such a "horizontal" partitioning of the disk, there is also a conditional "vertical" one. Since all heads are combined, they are always positioned over the same track number, each over its own disc. Thus, during the operation of the HDD, the heads, as it were, draw a cylinder:

While the HDD is working, in fact, it performs two commands: reading and writing. When it is necessary to execute a write command, the area on the disk where it will be performed is calculated, then the heads are positioned and, in fact, the command is executed. The result is then checked. In addition to writing data directly to disk, information also ends up in its cache.

If the controller receives a read command, first of all, it checks for the presence of the required information in the cache. If it is not there, the coordinates for positioning the heads are calculated again, then the heads are positioned and read the data.

After completion of the work, when the power supply of the hard drive disappears, the heads are automatically parked in the parking zone.

This is how a computer hard drive works in general terms. In reality, everything is much more complicated, but the average user, most likely, does not need such details, so we will finish this section and move on.

Types of hard drives and their manufacturers

Today, there are actually three main manufacturers of hard drives on the market: Western Digital (WD), Toshiba, Seagate. They fully cover the demand for devices of all types and requirements. The rest of the companies either went bankrupt, or were taken over by someone from the main three, or re-profiled.

If we talk about the types of HDD, they can be divided in this way:

1. For laptops, the main parameter is the device size of 2.5 inches. This allows them to be compactly placed in the laptop case;
2. For PC - in this case, it is also possible to use 2.5 ″ hard drives, but as a rule, 3.5 inches are used;
3. External hard drives are devices that are separately connected to a PC / laptop, most often acting as file storage.

There is also a special type of hard drives - for servers. They are identical to conventional PCs, but may differ in interfaces for connection, and greater performance.

All other divisions of HDD into types come from their characteristics, so we will consider them.

Hard drive specifications

So, the main characteristics of a computer hard drive:

• Volume - an indicator of the maximum possible amount of data that can be accommodated on the disk. The first thing they usually look at when choosing an HDD. This figure can reach 10 TB, although 500 GB - 1 TB is more often chosen for a home PC;
• Form factor - the size of the hard drive. The most common are 3.5 and 2.5 inches. As mentioned above, 2.5″ in most cases are installed in laptops. They are also used in external HDDs. 3.5″ is installed on the PC and on the server. The form factor also affects the volume, as more data can fit on a larger disk;
• Spindle speed - How fast do pancakes rotate? The most common are 4200, 5400, 7200 and 10000 rpm. This characteristic directly affects the performance, as well as the price of the device. The higher the speed, the greater both values;
• Interface - method (connector type) of connecting the HDD to the computer. The most popular interface for internal hard drives today is SATA (older computers used IDE). External hard drives are usually connected via USB or FireWire. In addition to those listed, there are other interfaces such as SCSI, SAS;
• Buffer volume (cache memory) - a type of fast memory (by type of RAM) installed on the HDD controller, designed for temporary storage of data that is most often accessed. The buffer size can be 16, 32 or 64 MB;
• Random access time - the time during which the HDD is guaranteed to write or read from any part of the disk. It fluctuates from 3 to 15 ms;

In addition to the above characteristics, you can also find indicators such as.

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 this type of device 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. And here, 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.

HDD is a data storage device - a hard disk drive. "HDD" is an abbreviation for the English phrase Hard Disk Drive. Other names for HDD: hard drive, hard drive, hard drive, screw, hard, tin, tin.

What is HDD for?

HDD is used to store information. Information stored on a hard drive is called data. The data on the disk is organized by means of a file system and is represented by files.

HDD is computer memory. Do not confuse with RAM. The hard drive is non-volatile memory, RAM is volatile.

Winchester is now the main storage device, and if you have a computer, then there is a screw.

Working principle of HDD

Hard disks, that is, HDDs, work in a similar way to a device that everyone has long forgotten about - a "player", with a rotating disk and a needle for playing music. The converting elements (read/write heads) used in hard drives are similar to the read/write heads used in VCRs and stereo cassette recorders to access information on magnetic media.

In hard drives, information is stored on a rotating metal or glass plate covered with a magnetic material. As a rule, a disk consists of several plates connected by a common rod - a spindle. Each plate is something like a vinyl record with a record played by a turntable. Information is usually stored on both sides of the plate.

As the disk spins, an element called the head reads or writes binary data to the magnetic media. Information is written to the disk using some encoding method, of which there are a great many. The encoding method and recording density is determined by the disk controller.

Without delving further into the description of the principle of operation of the HDD, we can say that the hard drive is, in fact, a super-player with a bunch (or maybe just one) of records inside. Although, of course, due to the complexity of the device, the player did not lie next to it.

The past and future of HDD

The very first HDD was developed by IBM in the early 70s.

In 1983, with the release of the first IBM PC / XT computer, a hard drive from Seagate Technology appeared in the lives of thousands of newly minted, yet wild users. The early hard drive interface, designed by Alan Shugart (founder of Seagate Technology), has been the de facto standard for HDDs for many years. In the future, Seagate's developments formed the basis of the ESDI and IDE interfaces. Shugart also developed the SCSI interface, which is now used in many modern computers.

By the way, now Seagate hard drives are the best-selling in Europe. And in Russia, who does not know the famous Barracudas?

The most important direction in the development of hard disk technology has always been an increase in their (drives) capacity. Progress in this area is especially driven by the ever-increasing demands of software. Increasing the capacity of drives is possible either by increasing the size of the drives themselves or by increasing the density of data storage. The HDD size limit has been reached, but the storage density limit has not yet been reached. But it didn't last long.

Need to know

1. HDD is a complex thing for storing information

2. The hard drive is short-lived and with constant use is unlikely to live more than three years

3. It is extremely undesirable to carry a hard drive (somewhere), turn it in your hands and generally remove it from the computer case. Winchester is very sensitive to vibration!

4. The internal structure of HDD is very complicated. If you once went to a circle of young radio amateurs, this does not mean at all that you can now repair hard drives. Repairing hard drives requires more than just a soldering iron!

5. Fans of poking around in hardware need to remember that by opening the HDA of a disk, you thereby put an end to both the information and the hard drive itself

6. In terms of storage security, storage media can be arranged in the following order (with increasing risk of data loss): head, paper, hard drive. Do not store important information on the HDD! And if you have to - always make backups!

7. If the information on the hard drive is not available for any reason, do not try to restore it! Most likely, you will only finally destroy it - it is better to contact professionals. Restoring information is not for you!

8. The word "HDD" is abusive and is not used in polite society, it characterizes something (to put it mildly) unreliable, short-lived and disgusting