How does a hard drive work? What are there hard drives? What role do they perform in a computer? How do they interact with other components? What parameters to consider when choosing and purchasing hard drive, you will learn from this article.
HDD- shortened name for " Hard Disk Storage". You will also find English HDD- and slang Winchester or for short Screw.
IN 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 saved on your hard drive. And the information on a computer is the most valuable thing! If the processor or video card fails, you can buy and replace them. But lost family photos from last summer's vacation or a year's worth of accounting data from a small business are not so easy to recover. Therefore, special attention is paid to the reliability of data storage.
Why is a rectangular metal box called a disk? To answer this question, we need to look inside and find out how the hard drive works. In the picture below you can see what parts the hard drive consists of and what functions each part performs. Click to enlarge. (Taken from the site itc.ua)
I also suggest watching an excerpt from a Discovery Channel program about how a hard drive works and works.
Three more facts you need to know about hard drives.
- The hard drive is the slowest part of the computer. When your computer freezes, pay attention to the hard drive activity indicator. If it blinks frequently or lights up continuously, it means the hard drive is executing commands from one of the programs while all the others are idle, waiting their turn. If the operating system is not fast enough RAM To run the program, it uses up space on your hard drive, which greatly slows down the entire computer. Therefore, one way to increase the speed of your computer is to increase the size of RAM.
- 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 rotating disk. The distance between the disk and the heads in modern devices is about 10 nm. If the disk is subjected to shock or vibration at this time, the head may touch the disk and damage the surface containing the data stored on it. As a result, the so-called " badblocks" - unreadable areas, due to which the computer cannot read any file or load the system. When turned off, the heads are “parked” outside the working area and shock overloads are not so terrible hard drive. Please do backups important data!
- The hard drive capacity is often slightly smaller than what the seller or manufacturer indicates. The reason is that manufacturers indicate disk capacity 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 storage capacity of your computer by connecting an additional hard drive or replacing the old one with a larger one, what will you need to know when purchasing?
First, look under the lid system unit your computer. You need to find out which hard drive interface the motherboard supports. Today the most common standards are SATA and moribund IDE. They are easy to distinguish by appearance. The picture on the left shows a fragment of a motherboard that is equipped with both types of connectors, but yours will most likely have 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, which will result in data transfer speeds being limited to the slower version. At the same time, the speed of the hard drive is even lower. Therefore, the potential of fast interfaces can only be revealed with the advent of new high-speed drives.
If you decide to purchase an additional SATA hard drive, check whether you have an interface cable like the one in the picture. It is not sold together with the disc. (Usually they are equipped with motherboard.) Also, among the connectors of the power supply there should be at least one free 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, capacity. As I mentioned above, please note that it will be slightly less than stated. The operating system and programs require 100 - 200 Gigabytes, which is quite a bit by modern standards. How much additional space you may need can be determined experimentally. Large volumes may be required, for example, for video recording high quality. Modern films in HD format reach several tens of gigabytes.
In addition, the main parameters include:
- Form factor- disk size. Discs of 1.8 and 2.5 inches are used in . For a desktop computer, you should purchase a 3.5-inch drive. They have the same SATA connectors and the laptop drive can work in a desktop computer. But small disks are made with an emphasis on compactness and low power consumption, and are inferior in performance to larger models. And they cost more.
- RPM- disk rotation speed. Measured in revolutions per minute ( RPM- abbreviation for revolutions per minute). The higher the rotation speed, the faster disk writes and reads information. But it also consumes more energy. Today the most common disks are with 5400 RPM And 7200 RPM. Lower RPMs are more common in laptop drives, drives large capacity(more than two terabytes) and so-called “green” disks, so named because of their reduced power consumption. There are also hard drives with rotation speed 10000 RPM And 15000 RPM. They are designed to work in highly loaded servers and have an increased reliability life, but they are also much more expensive than regular ones.
- Manufacturer. On at the moment There are several large manufacturers in the storage drive market. There is quite tough competition among them, 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.
Greetings to all blog readers. Many people are interested in the question of how a computer hard drive works. Therefore, I decided to devote today’s article to this.
A computer's hard drive (HDD or hard drive) is needed to store information after the computer is turned off, in contrast to RAM () - which stores information until the power supply is cut off (until the computer is turned off).
A hard drive can rightfully be called a real work of art, only an engineering one. Yes, yes, that's right. Everything inside is so complicated. At the moment, all over the world, the hard drive is the most popular device for storing information, it is on a par with devices such as flash memory (flash drives), SSD. Many people have heard about the complexity of the hard drive and are perplexed as to how it fits so much information, and therefore would like to know how the computer hard drive is structured or what it consists of. Today there will be such an opportunity).
A hard drive consists of five main parts. And the first of them is integrated circuit , which synchronizes the disk with the computer and manages all processes.
The second part is the electric motor(spindle), causes the disk to rotate at a speed of approximately 7200 rpm, and the integrated circuit maintains the rotation speed constant.
And now the third, probably the most important part is the rocker arm, which can both write and read information. The end of the rocker arm is usually split to allow multiple discs to be operated at once. However, the rocker head never makes contact with the discs. There is a gap between the surface of the disc and the head, the size of this gap is approximately five thousand times smaller than the thickness of a human hair!
But let's still see what happens if the gap disappears and the rocker head comes into contact with the surface of the rotating disk. We still remember from school that F=m*a (Newton’s second law, in my opinion), from which it follows that an object with a small mass and a huge acceleration becomes incredibly heavy. Considering the enormous rotation speed of the disk itself, the weight of the rocker head becomes very, very noticeable. Naturally, disk damage is inevitable in this case. By the way, this is what happened to the disk in which this gap disappeared for some reason:
The role of friction force is also important, i.e. its almost complete absence, when the rocker begins to read information, while moving up to 60 times per second. But wait, where is the engine that drives the rocker arm, and at such a speed? In fact, it is not visible, because it is an electromagnetic system that works on the interaction of 2 forces of nature: electricity and magnetism. This interaction allows you to accelerate the rocker to the speed of light, in the literal sense.
Part four- the hard drive itself is where information is written and read from; by the way, there can be several of them.
Well, the fifth and final part of the hard drive design is, of course, the case into which all other components are installed. The materials used are as follows: almost the entire body is made of plastic, but the top cover is always metal. The assembled housing is often called a “hermetic zone”. There is an opinion that there is no air inside the containment zone, or rather, that there is a vacuum there. This opinion is based on the fact that at such high speeds of rotation of the disk, even a speck of dust that gets inside can do a lot of bad things. And this is almost true, except that there is no vacuum there - but there is purified, dried air or neutral gas - nitrogen, for example. Although, perhaps in earlier versions hard drives, instead of purifying the air, they simply pumped it out.
We were talking about components, i.e. what does a hard drive consist of?. Now let's talk about data storage.
How and in what form is data stored on a computer’s hard drive?
Data is stored in narrow tracks on the surface of the disk. During production, more than 200 thousand of these tracks are applied to the disc. Each track is divided into sectors.
Maps of tracks and sectors allow you to determine where to write or read information. Again, all information about sectors and tracks is located in the memory of the integrated circuit, which, unlike other components of the hard drive, is located not inside the case, but outside and usually at the bottom.
The surface of the disk itself is smooth and shiny, but this is only at first glance. Upon closer inspection, the surface structure turns out to be more complex. The fact is that the disk is made of a metal alloy coated with a ferromagnetic layer. This layer does all the work. The ferromagnetic layer remembers all the information, how? Very simple. The rocker head magnetizes a microscopic area on the film (ferromagnetic layer), setting the magnetic moment of such a cell to one of the states: o or 1. Each such zero and one are called bits. Thus, any information recorded on a hard drive, in fact, represents a certain sequence and a certain number of zeros and ones. For example, photograph good quality occupies about 29 million such cells, and is scattered across 12 different sectors. Yes, it sounds impressive, but in reality it is huge amount bits occupies a very small area on the surface of the disk. Each square centimeter of a hard drive's surface contains several tens of billions of bits.
How a hard drive works
We just looked at hard device disk, each of its components separately. Now I propose to connect everything into a certain system, thanks to which the very principle of operation of the hard drive will be clear.
So, the principle on which a hard drive works next: when the hard drive is put into operation, this means that either writing is being done to it, or information is being read from it, or from it, the electric motor (spindle) begins to gain momentum, and since the hard drives are attached to the spindle itself, accordingly they go with it also begin to rotate. And until the revolutions of the disc(s) have reached a level such that an air cushion is formed between the rocker head and the disc, the rocker arm is located in a special “parking zone” to avoid damage. This is what it looks like.
As soon as the revolutions reach the desired level, the servo drive (electromagnetic motor) moves the rocker arm, which is already positioned in the place where information needs to be written or read from. This is exactly what contributes to integrated circuit, which controls all movements of the rocker.
There is a widespread opinion, a kind of myth, that at times when the disk is “idle”, i.e. No read/write operations are temporarily performed with it, and the hard drives inside stop rotating. This is truly a myth, because in fact, the hard drives inside the case rotate constantly, even when the hard drive is in power-saving mode and nothing is written to it.
Well, we have looked at the device of a computer hard drive in detail. Of course, within the framework of one article, it is impossible to talk about everything related to hard drives. For example, this article did not talk about - this is a big topic, I decided to write a separate article about it.
I found an interesting video about how a hard drive works in different modes
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There is a rule - the higher the skill in using a PC, the larger the hard drive it needs. Various collections of movies, games, pictures and home videos take up a lot of space in PC memory, so users try to increase its volume whenever possible. However, many people do not know what an ideal hard drive should be like, one that would have a lot of space, fit the configuration, and work quickly. That is why further information will be given on what parameters you should use to choose a drive, which one is more reliable and how to choose a device “for yourself”.
Rules for selecting a hard drive
It is worth immediately warning that “hard drives” (as hard drives are sometimes called) come in different varieties, and their choice is fraught with some difficulties. First of all, you need to rely on the following basic parameters of the HDD (hard drive):
- Volume. Figuratively speaking, the volume determines how much data the hard drive can contain before the “hard drive is full” warning lights up in front of you. Currently, you can purchase hard drives with a capacity of 1TB, which is enough for any collection (within reasonable limits) of the most “heavy” games or films.
- Manufacturing company. Currently, several large companies share the title of “best railway manufacturer”, but there is still no clear leader. Its reliability, performance and a good dozen other parameters directly depend on which companies create the hard drive.
- Cache sizes. Cache memory sets the speed of data processing by the device; to put it simply, the better this indicator, the faster the computer will boot, the faster data will be loaded, and some queries will be executed.
- Connector type. The connector determines whether the “hard” one will fit your computer or laptop. This parameter also affects the quality of the device’s throughput.
- Spindle rotation speed. This indicator also affects the speed of data processing, and accordingly, a higher-speed hard drive will record information faster.
Needless to say, the best hard drives will have all the maximum characteristics, and accordingly their purchase will cost a pretty penny. However, combining the device’s performance with your real needs will allow you to buy a good and inexpensive (comparatively) option that will ideally cover the user’s needs. QwertyShop experts described the information on selecting a hard drive http://qwertyshop.com.ua/zhestkie-diski as clearly and usefully as possible, so that everyone chooses the option correctly and to their taste.
With the development of computer technology, all devices in this category began to rapidly decrease in size, gradually “growing” into pocket-sized versions. The same situation happened with hard drives; as a result, external drives, which are easy to use and miniature in size. The price, of course, has also increased. However, it is not at all necessary to buy such device options; it all depends on the ultimate goal of the “upgrade”:
- Increased memory capacity. If the user's goal is simply to increase available memory, then there is no need to spend money on external device options. It is enough to select the hard drive format that matches your computer configuration, and then simply connect it as a secondary platform for storing data.
- The main hard drive for a computer. In this option, you also do not need to waste money on mobile types of hard drives, but purchase an internal hard drive with good write speed and capacity.
- Mobile data storage. If the user needs a large storage device that is easy to carry and use, then it is worth paying attention to external hard disk. As a rule, such devices have a USB connector, which allows you to connect them to any PC without opening the system unit and digging through the wires. In addition, external hard drives can be connected to other equipment - video players, laptops, TVs, and then read data from them.
As for internal devices, you should choose them according to the following parameters.
Hard disk capacity
If desired, you can purchase devices with different capacities, starting from 250 GB and ending with “terabytes”, however, practice shows that too large amounts of memory are unnecessary for most users. With the spread of the Internet, all data is stored not on the hard drive, but on the Internet, with the exception of games and programs. If a user considers himself to be “average,” then a HDD capacity of 500 GB is enough for him. Larger devices require more quantity resources for manufacturers, so they cost much more. 1TB is worth buying only for those people who like to collect collections of films, pictures and other data; such hard drives are also needed for games.
Cache memory
In fact, the disk cache plays the role of operational space where data of primary importance is loaded. The higher the setting, the faster tasks on the computer will be completed. Standard hard the disk has clipboard volumes (another name for this section memory) from 8 to 32 MB. This is quite enough for the average user who does not program, does not like powerful and productive games, but simply surfs the Internet and watches videos. The most productive HDD will be a device with 64 MB.
Spindle speed
The hard drive itself looks like a large disk that spins during operation. It is driven by the spindle, and the head, which has direct contact with the disk, is responsible for reading and writing data. The faster the spindle rotates, the faster the hard drive performs its task - processing information. The average hard drive has a rotation speed of 5400 rpm; more expensive and productive models have a speed of 5900 or 7200 units. Again, if the user wants a “faster” disk, then it’s worth looking at a HDD with a speed of 10,000 units - one of the most functional options today.
Important information: do not also forget about new types of devices that are gradually taking over the market - drives SSD systems. This option differs from the standard in the type of device - SSD drives operate on solid media. No disks, no spindles, only data storage chips. Such hard drives have much faster operating speeds and do not make noise (more on that later), but the cost and reliability of these HDDs are much less. The cost is understandable, but reliability needs to be sorted out. The thing is that it is impossible to recover data from an SSD - if the voltage jumps to the upper limit, then this version of the technique “burns out completely”.
Interface
With the development of computer technology, hard drives have changed several times the connector through which it is connected to the PC. The modern version has a SATA connector (USB for external ones); it is used in almost all models of computers and disks. However, another interface has not yet completely gone out of use - IDE. The SATA version has much greater bandwidth, so such a hard drive will process data faster, but if the user has an old PC, he should be careful - these two interfaces are incompatible.
Manufacturer
As for the manufacturer of this equipment, expert opinions vary greatly. Most of them believe that the leading companies involved in the development of railways are Western Digital and Hitachi. It is these companies that create the most reliable devices - their temperature is always at the same level, breakdowns occur infrequently, and functionality is at its best. Some analysts put Seagate in opposition to WD (Western Digital). The most unreliable, but popular HDDs are disks Samsung(editorial opinion).
Statements regarding the unreliability of Samsung drives are made based on:
1. number of warranty returns in the QwertyShop retail network;
2. analysis of reviews in the Yandex.Market service;
3. personal experience editions with a short service life of disks from this manufacturer.
Industry leaders, Western Digital, have special color codes for the reliability and quality of devices.
Noise level
Some users are annoyed by the noise that the hard drive makes during operation. It can crack, hum, rattle, and this whole cacophony begins when power is supplied to the computer and ends when it is turned off. It is believed that Western Digital devices make the least noise during operation, but this is a subjective opinion of the company’s fans, so it’s a stretch to take this into account. There are no other parameters for choosing a disk based on the level of noise it produces, so you have to hope for luck.
If the hard drive operates in “difficult” conditions for it, it will quickly fail. To delay this moment as long as possible, you should consider the following expert advice.
- Use a UPS. A high-quality uninterruptible power supply will protect the HDD from voltage surges - the main killer of technical equipment.
- Use control programs. There are a number of programs that regularly scan the condition of the hard drive - temperature, spindle speed. If you look at them from time to time, you can catch the moment when the disk began to “scrap” and send it in for repair in time.
- Provide cooling. The HDD generates a lot of heat during operation, sometimes so much that the standard PC cooling system cannot cope with the load. If a user experiences this situation, it is worth adding a couple of fans to the system unit.
- Choose the right power supply. If the user has an uneven power supply installed, it may power the hard drive high voltage, which is guaranteed to “kill” the device.
Many users are interested in the hard drive device. And for good reason, because today the most common storage device on a computer is the HDD. Next, the principles of its operation and structure will be discussed.
A Winchester is essentially like a record player. It also contains the platters and read heads. However, the HDD device is more complex. If we disassemble the hard drive, we will see that the plates are mostly metal and covered with a magnetic layer. This is where data is written. Depending on the volume of the hard drive, there are from 4 to 9 plates. They are mounted on a shaft, which is called a “spindle” and has high speed rotations from 3600 to 10000 rpm for consumer products.
Next to the wafer block there is a read head block. The number of heads is determined by the number of magnetic disks, namely one for each disk surface. Unlike the player on hard drives the head does not touch the surface of the plates, but hovers above it. This eliminates mechanical wear. Since the plates have a high rotation speed, and the heads must be at an extremely small constant distance above them, it is very important that nothing can get into the housing. After all, the slightest speck of dust can cause physical damage. That is why the mechanical part is hermetically sealed with a casing, and the electronic part is taken outside.
Some users are interested in how to disassemble a hard drive. You need to understand that disassembling a working drive involves breaking its seal. And this, in turn, will render it unusable. Therefore, you should not do this unless you are ready to lose all the data on the storage medium. If you don’t have an urgent need to open the drive, but are just curious about what a hard drive is made of, you can look at a photo of a disassembled HDD.
This is why hard drives are magnetic disks during repairs, they are disassembled and assembled in a special laminar flow hood. Using a highly purified air supply system and tightness, it maintains the environment necessary for such work. By disassembling your disk at home, you will definitely render it inoperable.
When inoperative, the read heads are located next to the wafer block. This is also called “parking position”. A special device brings the heads into the working area only when the disk has accelerated to the required speed. They all move together, not each one separately. This allows you to have quick access to all data.
The electronic board, or controller, is usually attached to the bottom of the hard drive. Nothing protects it, and this makes it quite vulnerable to mechanical and thermal damage. It is she who controls the mechanics. The laptop hard drive differs from the standard 3.5-inch only in size. The principle of operation of a hard drive is exactly the same. They can differ only in the number of magnetic pancakes and storage capacity.
As you can see, the hard drive device is subject to shock, shock, scratches, significant temperature changes and power surges. And this makes it not a completely reliable information carrier. It is because of this that the hard drive on a laptop fails more often than on a desktop PC. After all portable devices They are constantly shaken, sometimes dropped, taken out into the cold or placed in the sun. And this, in turn, negatively affects the hard drive.
To extend the deadline HDD operation, do not subject it to drops or shocks, make sure that there is sufficient ventilation of the case, and perform any manipulations with the disk only when the power is turned off. These shortcomings have led to the emergence of a new type of SSD hard drive. They are gradually replacing HDDs, which once looked like great storage media.
Logical device
We found out what a hard drive looks like inside. Now we will analyze its logical structuring. Data is written to the computer's hard drive on tracks that are divided into specific sectors. The size of each sector is 512 bytes. Consecutive sectors are combined into a cluster.
When installing a new HDD, you need to format it, otherwise the computer simply won’t see free space on the drive. Formatting can be physical or logical. The first involves dividing the disk into sectors. Some of them may be defined as “bad”, that is, unsuitable for recording data. In most cases, the drive is already formatted in this way before being sold.
Logical formatting involves creating a logical hard section disk. This allows you to significantly simplify and optimize your work with information. A specific area of the drive is allocated for a logical partition (or, as it is also called, a “logical disk”). You can work with it as with a separate hard drive. To understand how a hard drive works with its partitions, it is enough to visually divide the hard drive into 2-4 parts, depending on the number of logical volumes. Each volume can have its own formatting system: FAT32, NTFS or exFAT.
Technical data
HDDs differ from each other according to the following data:
- volume;
- spindle rotation speed;
- interface.
Today, the average hard drive capacity is 500-1000 GB. It determines the amount of information that you can write to the media. The spindle speed will determine how quickly you can access data, that is, read and write information. The most common interface is SATA, which replaced the already obsolete and slow IDE. They are different from each other throughput and the type of connector connected to the motherboard. Note that the disk modern laptop can only have SATA interface or SATA2.
This article examined how a hard drive works, its operating principles, technical data and logical structure.
Many of you know that all information on a 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 answer correctly. It is very difficult for people far from programming to imagine how information can be stored on some piece of hardware. This is not a box or a piece of paper on which this very information can be written down and hidden in the 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 a “Winchester”. It is designed to store information in the form of photographs, pictures, letters, books of various formats, music, films, etc. Externally, 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 similar to an old vinyl record player.
Inside this metal box there are round aluminum or glass disk 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 work hard The disk is divided into several partitions. This division is conditional. This is done using the operating system or special programs. The new partitions are called logical disks. They are assigned the letters C, D, E or F. Usually installed on the C drive, and files and folders are stored on other drives so that if the system crashes, your files and folders are not damaged.
Watch a video about what a hard drive is:
Basic characteristics of hard drives
- Form factor is the width of the hard drive in inches. Standard size for desktop computer 3.5 inches, and for laptops 2.5 inches;
- Interface- V modern computers used connection to motherboard SATA different versions. SATA, SATA II, SATA III. Older computers use the IDE interface.
- Capacity- This maximum quantity The information that a hard drive can store is measured in gigabytes;
- Spindle speed is the number of spindle revolutions per minute. The higher the disk rotation speed, the better. For operating systems, you need to install disks of 7,200 rpm and higher, and for storing files you can install disks with lower speeds.
- MTBF– this is the average time between failures calculated by the manufacturer. The larger it is, the better;
- Random access time is the average time required for the head to position itself on an arbitrary section of the wafer. The value is not constant.
- Impact resistance is the ability of a hard drive to withstand pressure changes and shocks.
- Noise level which the disk emits during operation is measured in decibels. The smaller it is, the better.
It already exists now SSD drives(solid-state drive in simple translation - solid state drive), which have neither a spindle nor plates. It is a storage device based on memory chips.
SSD drives are completely quiet and have very good speed reading and writing. 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.
