The term " HDD" is short for " Hard Disk Drive» ( HDD). English name - " hard drive» ( HDD or HMDD with the addition of the word Magnetic"). In addition to the abbreviation "hard drive", there are other slang names for this device: " Winchester" (or " screw»), « harddisk" (or " hard»).
Name " Winchester”, According to one version, the drive was received thanks to IBM, which released the model 3340 hard drive in 1973, which for the first time combined disk platters and read heads in one one-piece housing. When developing the drive, engineers used the internal designation " 30-30 ”, which meant two modules of 30 MB at the maximum layout.
Project Manager Kenneth Haughton in consonance with the name of the popular hunting rifle (at that time) "Winchester 30-30" proposed to call the disk being developed "Winchester". However, in the US and Europe back in the 1990s. The name "Winchester" has practically fallen into disuse. And in Russian, it has been preserved and even received a semi-official status. In computer slang, it has been shortened to " screw", which is the most commonly used variant of the name.
HDD- This is a device for storing information, the operation of which is carried out on the principle of magnetic recording. The hard drive is used as the primary storage medium in most modern .
In HDD, in contrast to the so-called "floppy disk" (or floppy disk), information is recorded on rigid plates (aluminum, glass or ceramic) coated with a thin layer of ferromagnetic material, which, most often, is chromium dioxide. Hard drives use one or more platters on a common axis.
In operating mode, the reading heads do not touch the plates due to the layer of air flow formed near the surface of the plates during their rapid rotation. Between the head and the plate, a distance of several nanometers is maintained (for modern disks, about - 10 nm). When the disks are not rotating, the heads are at the spindle itself or in a safe area outside the disk, where their mechanical contact with the disks is excluded. The absence of mechanical contact between parts ensures a long service life of the device.
Initially, there was a wide variety of hard drives on the market, produced by many companies. As competition intensified, most manufacturers either switched to other types of products or were bought by competitors.
Quite a noticeable mark in the history of railway was left by the company Quantum. Another leader in the production of discs was the company Maxtor, which bought the hard drive business from Quantum in 2001. In 2006 Maxtor and Seagate merged. In the mid 90s. there was a famous company Conner, which also merged into Seagate.
In the early 90s there was a company Micropolis, which produced expensive premium hard drives. However, when it released the first 7200 rpm discs (an industry first), it used bad Nidec mainshaft bearings. Micropolis suffered big losses on returns and was bought by the same Seagate.
Today, most of all hard drives are produced by a small number of companies: Seagate, Samsung, western digital, former division IBM, now owned Hitachi. Until 2009 Fujitsu produced hard drives for laptops but then transferred all their production to the company Toshiba. Toshiba is now the main manufacturer of 1.8" and 2.5" laptop hard drives.
14.05.2010
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Last edit: 2011-11-17 17:06:09
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Many have heard words like HDD , « HDD», « screw" or " Winchester". All these words are synonyms for the same device. HDD - This is a device for storing and storing information, which is based on the principles of magnetic recording. The hard drive in most modern computers is the main data storage device. It retains information even when the computer is turned off, it can also be removed from the computer's system unit and connected to another PC .
The history of the hard drive Main difference hard drive from diskettes - this is the recording of information on hard plates (aluminum or glass) coated with a ferromagnetic material, in most cases chromium dioxide. Winchesters are most often used as non-removable storage medium , but in recent years has been invented removable hard drive , which has been widely used. The hard drive is usually combined with a drive, a drive and an electronics unit.
For the first time in the computer market "screw" appeared back in 1957. He was born thanks to the company IBM long before the advent of the personal computer. It was capable of holding 5 MB of information and cost crazy money. A little later, 10 was developed MB hard drive, but for PC. Winchester consisted of 30 tracks and 30 sectors each. After marking "30/30" of the brand of the same name with the popular carbine " Winchester» the drive was named colloquially « Winchester” or abbreviated “screw”. On the territory of Europe and the USA, this term disappeared back in the 90s, and only in Russia it continues to be called in this way in slang.
Winchester consists of several metal discs coated with a special substance that can store a magnetic field. The number of metal plates in a hard drive varies from one to three. These discs have a very smooth surface and excellent balance. These qualities are necessary for high rotation speed. Special magnetic heads, located one at a time on different sides of the discs, allow you to record on them. heads have magnetoresistor properties that are sensitive to changes in the magnetic field through changes in the strength of the current excited in the head. The received signal is read and then digitized. Itself head under the influence of current pulses, it is capable of creating a magnetic field. Depending on the direction of the magnetic moment, sections of the disk are magnetized.
Data on disks is stored in so-called tracks. In the course of the hard drive, the magnetic heads change their location from one track to another. In modern HDD used to change the position of the magnetic heads solenoid drive unit.
A track consists of sectors, each of which stores 512 bytes of data. The smallest disk space is a sector. The product of cylinders, sectors and the number of heads is the maximum volume that can be stored on a hard drive. Almost all manufacturers strive to make tracks as dense as possible and reduce the number of discs.
During work hard drive bad sectors and tracks appear. During low-level formatting, they are specially marked and are not taken into account in the future when the hard drive is working.
Basic parameters of the hard disk
Main characteristic hard drive is an capacity(the amount of information that can be contained). Capacity is measured in gigabytes ( GB). One GB equals 1000 megabytes ( MB). In turn, 1MB is equal to 1000 kilobytes ( KB). But in the information world, a slightly different system of counting has been adopted. Instead of 1000, they count 1024. You need to pay attention to this. When diagnosing a computer, the operating system will indicate fewer GB than specified by the manufacturer.
Another important characteristic is the spindle speed. This indicator directly affects the speed of the hard drive (that is, how quickly information will be exchanged with other computer devices). The higher the rotation speed, the faster the reading and writing of hard disk information. For desktop computers, a good indicator is considered 7200 rpm . At higher rotation rates, the speed of the hard drive increases significantly.
Another important parameter is the random access time, which is closely related to the rotation speed. Most manufacturers do not indicate this figure in sales, but if you dig around on the Internet, such information can be easily found. The random access time shows how long the hard drive will read or write information on any of the sections of the disk. This parameter is measured in milliseconds. The lower the indicator, the higher the speed of the hard drive.
It is important to know what interface is equipped with " screw". In simple words, the hard drive connector with which it is attached to the motherboard. Was earlier IDE but now it has been replaced SATA. The latter are equipped with all modern hard drives , they are faster and more convenient to install. It is necessary to consider what interface the motherboard is equipped with. If the connectors do not match, connection will not be possible.
There are also disks specifically for servers. They are the same size as normal HDD, but much faster at work. The rotation speed of such devices reaches 15,000 rpm. They are more reliable than desktop hard drives. Server drives come with a serial interface SAS And SATA and parallel SCSI.
Not so long ago, external hard drives were invented. They are very convenient to use, have a smaller size and weight, large amounts of data. They are also called mobile media or "big flash drive". With the help of external HDD It is convenient to transfer various information in the form of audio recordings, office archives and multimedia files. The controllers are capable of supporting USB 2.0, 3.0 and FireWire.
The average rotation speed of hard drives for laptops is 5400 rpm or 4200 rpm. Also, they must be impact resistant.
Main connection interfaces
USB– serial data transmission. Bandwidth USB 1.1 - 12 MB / s, USB 2.0 - 480 MB / s USB 3.0 - 5 GB / s.
IDE– data transmission is parallel. Bandwidth approximately 133 MB/s. This interface is commonly used in desktop computers and laptops.
SATA – parallel data transfer. The throughput is about 300 MB/s. The main competitor of the IDE. SATA is more resistant to interference and slightly better than IDE.
SCSI– parallel data transfer. It is mainly used when working with servers. It is distinguished by high performance and reliability.
Serial Attached SCSI (SAS)– serial transmission of information. Improved version of SCSI with improved performance and reliability.
firewire- sequential transmission. The speed is close to 400 MB/s. For working with video files, this is the best choice.
Manufacturers
At the end of the last century, there were many manufacturing companies on the computer market. hard drives . But at the moment the number of firms has decreased markedly. Some could not stand the competition, others were bought by more powerful competitors, others began to manufacture products other than hard drives.
In the mid-90s, hard drives were produced by the company Conner Peripherals, later acquired Seagate, And Micropolis. The last one did high qualitySCSI premium drives for servers. The company produced very expensive products, but due to the supply of low-quality spindle bearings, the company suffered huge losses on the return and replacement of hard drives, and subsequently went bankrupt. It was also bought out by Seagate.
Popular and now the products of the Japanese company Fujitsu. Now she is betting on the production of hard drives for laptops and SCSI drives. But it is no longer the same turnover as it was in the last century. In 2001, the firm suffered a serious setback. In that year, the controller chip massively failed, as a result, the company suffered serious financial losses, after which it has not yet recovered. But before the breakdown, the Japanese company was considered a leader in the production of hard drives. Winchesters of this manufacturer were distinguished by excellent characteristics of rotating surfaces. In 2009 mass production of hard drives Fujitsu moved to Toshiba .
Until the beginning of 2000, the disks of the IBM division were considered reference. But after mass failures from drives for PC due to oxidation of the contacts of the german bank connector, the American branch suffered significant financial losses, and was sold Hitachi.
Quantrum left a bright mark on history, but due to massive breakdowns HDD in series SH, she also dropped out of the computer market.
Maxtor was considered the leader in its field. In early 2001, she buys out the division Quantrum, which is engaged in the production of hard drives and inherits a train of problems of the acquired company due to "thin" drives. In 2006, it merged with the company Seagate .
Spring 2011 was the last for Hitachi,very popular in the market hard drives . She's acquired western digital, and in the same year, Samsung's HDD division was taken over by Seagate.
Now there are only three manufacturers left on the hard drive market - Seagate, Western Digital and Toshiba . But recently, due to the development of SSD technology and the emergence of external hard drives, the number of companies ready to offer new technologies and developments begins to increase again.
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HDD ("winchester", hdd, hard disc drive - eng.) - an information storage device based on magnetic plates and the effect of magnetism.
Applies everywhere in personal computers, laptops, servers and so on.
Hard disk device. How a hard drive works.
In the floor sealed the block contains double-sided plates, with applied on them magnetic layer planted on motor shaft and rotating at a speed of 5400 revolutions per minute. The block is not completely sealed, but most importantly, it does not let through small particles and does not allow humidity fluctuations. All this adversely affects the life and quality of the hard drive.
In modern hard drives, the shaft is used. This gives less noise during operation, significantly increases durability and reduces the chance of jamming the shaft due to collapsed.
Reading and writing is done with head block.
In working order, heads soar above the disk surface at a distance ~10nm. They are aerodynamic and rise above the disk surface due to updraft from the rotating plate. Magnetic heads can be located on both sides plates, if magnetic layers are deposited on each side of the magnetic disk.
The connected head unit has fixed position, that is, the heads move all together.
All heads are controlled by a special drive unit based on electromagnetism.
Neodymium magnet creates a magnetic field, in which the head unit can move with a high reaction speed under the influence of current. This is the best and fastest way to move the block of heads, and after all, once the block of heads was moved mechanically, with the help of gears.
When the disc is turned off, to prevent the heads from sinking onto the disc and damaged him, they clean up in head parking area(parking zone, parking zone).
It also allows you to transport offline hard drives without any special restrictions. In the off state, the disk can withstand heavy loads and not be damaged. In the on state, even a small push at a certain angle can destroy the magnetic layer of the plate or damage the heads when touching the disk.
In addition to the sealed part, modern hard drives have an outer control board. Once upon a time, all control boards were inserted into the computer motherboard in expansion slots. It was not convenient in terms of versatility and capabilities. With hard drives these days, all the drive electronics and interfaces are located on a small circuit board at the bottom of the hard drive. Thanks to this, it is possible to configure each disk for certain parameters that are beneficial from the point of view of its structure, giving it a gain in speed, or quieter operation, for example.
To connect the interface and power, standard common connectors are used / and Molex/Power SATA.
Peculiarities.
Hard drives are the most capacious custodians of information and regarding reliable. The volume of disks is constantly growing, but recently this is due to some complexities and for further expansion of the volume, new technologies are required. We can say that hard drives have practically gone straight in achieving maximum capabilities. The spread of hard drives was mainly facilitated by the ratio pricevolume. In most cases, a gigabyte of disk space costs less than 2.5 rubles.
Pros and cons of hard drives vs.
Before the advent of solid state SSD(solid state drive) - drives, hard drives had no competitors. Now hard drives have a direction to aim for.
Cons of hard drives(hard drive)(ssd) drives:
- low sequential read speed
- low access speed
- slow reading speed
- slightly slower write speed
- vibrations and slight noise during operation
Although on the other hand, hard drives have other more weighty the benefits to which SSD accumulators strive and strive.
pros hard drives (hard drive) compared to solid state (ssd) drives:
- significantly better volume price
- the best indicator of reliability
- higher maximum volume
- in case of failure, many times more chance to recover data
- the best option for use in media centers, due to its compactness and large capacity 2.5 drives
About what worth paying attention when choosing a hard drive, you can see in our article "". If you need hard drive repair or data recovery, you can refer to.
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 drive 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, purely physically, it would be very difficult to damage the surface of the data disk. 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 from 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 data damage. 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.
HDD(HDD, VINT, WINCHESTER) is an information storage device in a personal computer. A hard drive is designed to store and transfer information. On a hard disk, data is stored on the magnetic surface of the disk. Information is recorded and removed using magnetic heads. A hard drive can contain several platters - disks. The motor that rotates the disk is turned on when power is applied to the disk and remains on until power is removed. The motor rotates at a constant speed, measured in revolutions per minute (rpm). Data is organized on the disk in cylinders, tracks, and sectors. Cylinders are concentric tracks on disks, one above the other. The track is then divided into sectors. The disc has a magnetic layer on each side. Each pair of heads is dressed, as it were, on a “fork” that wraps around each disk. This "fork" is moved over the surface of the disk using a separate servo motor (and not a stepper motor, as is often mistakenly thought - a stepper motor does not allow you to quickly move over the surface). All hard disks have spare sectors that are used by its management scheme if bad sectors are found on the disk.
Hard drive device:
Hard drive interfaces
A drive interface is a set of electronics that provides information exchange between the device controller (cache buffer) and a computer. An interface is the way a hard drive interacts with a computer's motherboard. It is a set of special lines and a special protocol (a set of rules for data transmission). That is, purely physically, it is a cable (cable, wire), on both sides of which there are inputs, and on the hard drive and the motherboard there are special ports (places where the cable is connected). Thus, the concept of an interface includes a connecting cable and ports located on the devices connected by it.
IDE- translated from English "Integrated Drive Electronics", which literally means - "built-in controller". This was later called the IDE as an interface for data transfer, since the controller (located in the device, usually in hard drives and optical drives) and the motherboard had to be connected with something. It (IDE) is also called ATA (Advanced Technology Attachment), it turns out something like "Advanced Technology Attachment".
What can I say, although the IDE was very slow (the bandwidth of the data transfer channel ranged from 100 to 133 megabytes per second in different versions of the IDE - and even then purely theoretically, in practice it is much less), but it allowed you to connect two devices to the motherboard at once using one loop.
Moreover, in the case of connecting two devices at once, the bandwidth of the line was divided in half. However, this is far from the only drawback of the IDE. The wire itself, as can be seen from the figure, is quite wide and, when connected, will take up the lion's share of the free space in the system unit, which will negatively affect the cooling of the entire system as a whole. All in all IDE is outdated morally and physically, for this reason, the IDE connector is no longer found on many modern motherboards, although until recently they were still installed (in the amount of 1 pc.) On budget boards and on some boards in the middle price segment.
The next, no less popular than the IDE at one time, interface is SATA (Serial ATA), a characteristic feature of which is serial data transmission. It is worth noting that at the time of this writing, it is the most massive for use in a PC.
Interfaces SATA, SATA 2(II), SATA 3(III)
In 2002, the first hard drives appeared, with a progressive, at that time, interface SATA . The maximum data transfer rate of which was 150 MB / s.
If we talk about the benefits, then the first thing that catches your eye is the replacement 80-wire loop (Fig. 1), to a seven-wire SATA cable (Fig. 3), which is much more resistant to interference, which made it possible to increase the standard cable length from 46 cm to 1 m. Also, the corresponding SATA connectors were developed (Fig. 4), which are several times more compact than the connectors of the previous IDE standard. This allowed more connectors to be placed on the motherboard, now on new motherboards you can find more than 6 SATA connectors, against the traditional 2-3 IDE, in older motherboards focused on this standard.
Further, the SATA II standard appeared, the data transfer rate reached 300 MB / s. This standard has many advantages, among them: Native Command Queuing technology (it was it that made it possible to achieve a speed of 300 MB / s), hot plugging of disks, executing several commands in one transaction, and others.
Well, in 2009, the interface was introduced SATA 3 . This standard provides for data transfer at a speed 600 MB/s (for hard drives, "oh" how redundant).
As an asset of interface improvements, you can add more efficient power management and, of course, an increase in speed.
It should be noted that SATA, SATA II and SATA III, are completely compatible.
- 1956 - IBM 350 hard drive as part of the first mass-produced IBM 305 RAMAC computer. The drive occupied a box the size of a large refrigerator and had a weight of 971 kg, and the total memory capacity of 50 thin disks with a diameter of 610 mm rotating in it covered with pure iron was about 5 million 6-bit bytes.
- 1980 - First 5.25" Winchester, Shugart ST-506, 5MB.
- 1981 - 5.25" Shugart ST-412, 10 MB.
- 1986 - SCSI, ATA standards.
- 1990 - maximum capacity 320 MB.
- 1995 - maximum capacity 2 GB.
- 1997 - maximum capacity 10 GB.
- 1998 - UDMA/33 and ATAPI standards.
- 1999 - IBM releases Microdrive with a capacity of 170 and 340 MB.
- 2000 - IBM releases Microdrive with a capacity of 500 MB and 1 GB.
- 2002 - ATA / ATAPI-6 standard and drives with a capacity of over 137 GB.
- 2003 - the emergence of SATA.
- 2003 - Hitachi releases 2 GB Microdrive.
- 2004 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 2.5 and 5 GB.
- 2005 - maximum capacity 500 GB.
- 2005 - Serial ATA 3G standard.
- 2005 - the emergence of SAS.
- 2005 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 8 GB.
- 2006 - application of the perpendicular recording method in commercial drives.
- 2006 - the appearance of the first "hybrid" hard drives containing a block of flash memory.
- 2006 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 12 GB.
- 2007 - Hitachi introduces the first commercial 1TB drive.
- 2009 - based on 500 GB Western Digital plates, then Seagate Technology LLC released 2 TB models.
- 2009 - Samsung released the first USB 2.0 hard drives
- 2009 - Western Digital announced the creation of 2.5-inch HDDs with a capacity of 1 TB
- 2009 - the emergence of the SATA 3.0 standard.
- 2010 - Seagate releases a 3TB hard drive.
- 2010 - Samsung releases a hard drive with platters that have a recording density of 667 GB on a single platter
- 2011 - Western Digital released the first disc on 750 GB platters.
