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Data storage. Internal and external storage

Storage devices and information carriers.

Information storage device - a device that reads and / or writes information.

Information storage devices are:

· internal and external:

· with removable and non-removable media;

· stationary and portable.

Internal drives are located in the PC system unit and are connected to special connectors on the motherboard.

External and portable drives are located in their own case and are connected to the computer via standard ports input / output. External storage devices are used for backing up and storing information, as well as for transporting data from one computer to another.

Information carrier Is a device on which information is directly recorded (stored), for example, a disk, a cassette with a magnetic tape, etc.

The drive and the storage medium can be made in one housing, i.e. make up one whole, for example, a hard disk HDD (Fig. 13).

Rice. 13. Hard disk drive HDD

The drive can have removable media, for example:

At the FDD drive removable media - floppy disk ( Floppy disk);

DVD-RW drive (fig. 14) removable storage medium - DVD disc.

Rice. 14. DVD-RW drive

In some cases, the division into drive and media is arbitrary. For example, internal storage of information random access memory (RAM ) and portable storage FLASH - the card is both a storage device and an information carrier.

Basic storage and storage media

Storage device	Russian designation	International designation	Drive type	Carrier	Media type
RAM			interior	she
			interior	she
(hard disk drive)			interior	HDD	non-removable built-in
FDD drive (floppy disk drive)			interior	floppy disk	removable portable
CD -ROM, CD -RW - drive for reading and writing CD-disks			interior	CD disc (compact disc)	removable portable
DVD -RW - drive for reading and writing CD and DVD-disks		DVD-R DVD-RW	interior		removable portable
FLASH card			external, portable	she

The main characteristic of a medium (drive) is its capacity, i.e. the maximum amount of information that can be recorded on this device. Storage capacity is measured in the following units:

	designation	International designation
kilobyte
megabyte
gigabyte

Lately floppy disks and CDs -disks are outdated, in the near future they will cease to be used and are actively replaced by more capacious media FLASH -cards (fig. 15) and DVD discs.

Rice. 15 .. FLASH -card

The capacity of the main storage media.

go out of use

DVD discs can be single-sided or double-sided, single-layer and double-layer

FLASH card

256 Mb, 512 Mb,

Internal media / storage media

standard for Windows XP

Hard HDD disk

Typical HDD capacity of a modern PC

External storage devices somehow unexpectedly entered our life. One might say in a leap. Nowadays, people highly appreciate the mobility of information, as well as the speed of its transmission. That is why an external storage device is a very valuable device that allows you to quickly exchange movies, games and other files (it should be noted, even of considerable size) between two computer devices.

general information

The question that arose in connection with the problem of storing user data, as well as access to them, is quite relevant. This problem is very acute in families, where everyone tries to knock out as much space on the computer as possible just for their own needs. And an external drive can easily be the solution to such problems.

The optimal currently are, of course, various network storages, which in many companies are located right inside buildings. In general, they have a lot of advantages. Previously, creating a NAS required the purchase of a separate computer to play this role. Now, with the development of wireless technologies, this is no longer necessary. It is enough to put a wireless router into operation and the problem is solved.

Modern models are available with support for USB 3.0 ports. And this also has weight, since functionality expand significantly. What can you think of even better than a network resource located at home, which, if necessary, is quite realistic to take with you on a trip? And this device will have such a mobile size that it will not burden absolutely anyone with its carrying!

In general, an external USB drive will be the solution to several problems at once. Models of external hard drives differ in characteristics, and in this article we will analyze several devices, get acquainted with them in general and in general, and figure out what advantages and disadvantages they have. This is done so that anyone who wants to can then go to the store, and based on the material read, if necessary, choose for themselves a model of an external drive.

So many hard drives currently have an interesting and innovative interface. It's about 3.0. They also come in a large form factor. Next, we'll talk about whether it makes sense to purchase such disks, which are large enough and require power from an external source.

ADATA HD 710

This external storage device is available in different versions, which differ in the amount of built-in memory. We are talking about the allocation of 500 gigabytes, 1 terabyte, and 2 terabytes. 500 GB, in our opinion, is now not enough for active use of the hard drive. But 1, and even more so 2 TB will be an excellent solution.

This external drive in three colors at once. The following colors are available: blue, yellow, black. All hard drives in this series are shockproof and waterproof. You can easily lay the USB cable in the groove that was specially secured around the disk enclosure. Thus, the developers of the device solved the problem with the convenience of storing the cable. Its length is about 30 centimeters. And to be more precise, 31. The dimensions are quite average: with its weight of 220 grams, this is an external USB stick 3.0 has dimensions of 132 by 99 by 22 millimeters.

Hard drive. External hard drive HGST Touro Mobile MX3

This model, like its predecessor, has three modifications at once, equipped with different volumes of built-in long-term memory. We are talking about variations of 500 gigabytes, as well as models with a capacity of 1 TB and 1.5 TB.

Among the shortcomings, it is worth noting the lack of legs that could fight vibration hard disk during his work. But the use of matte plastic as a material for the manufacture of the case cannot be unambiguously considered. The USB cable doesn't go anywhere. It is 43 centimeters long. This external hard drive is 126 millimeters long, 80 millimeters wide, and 15 millimeters high.

Seagate Expansion Portable

All Seagate models in the Expansion series of external portable hard drives have the same form factor. It is 2.5 ''. The lineup of the series has three memory drives, which have the corresponding volumes. These are, according to the standard, 500 gigabytes, 1 and 2 TB.

Like the model we reviewed earlier, the Seagate Expansion Portable does not have rubber feet. The body of the series devices is made of matte plastic. These external storage devices have a 44 cm USB cable. The dimensions of the hard drive are 122.3 millimeters long, 81.1 millimeters wide, 15.5 millimeters high. The mass of the drive is 170 grams.

Seagate Expansion

Models of this series differ from their predecessors not only in memory size, but also in large form factor. It is 3.5 ''. Thus, the models automatically increase in size, weight, and also require power. The case of such hard drives is made of the same matte plastic. To combat vibration that occurs during operation of the device, there are four rubber feet on the bottom of the device. In the model range of this series, you can see external hard drives, the amount of built-in memory of which is 1, 2, 3, 4 and 5 terabytes.

The USB 3.0 cable is 118 centimeters long. A dedicated power adapter is required for the hard drive to function. It operates at 12 volts as well as 1.5 amperes. In length, such a storage device reaches 179.5 mm. It is 118 millimeters wide and 37.5 mm high. In this case, the mass of the drive is equal to 940 grams.

Silicon Power Armor A80

External drives of this series have a good case, protected from moisture penetration, as well as from mechanical damage. The outer surface of the hard drive is made of anodized brushed aluminum. There are no rubber feet to withstand the vibration that occurs when working with the drive.

The lineup consists of drives with three different memory sizes. These are 1 and 2 terabytes, as well as 500 gigabytes. The models in the series are slightly different from all external drives that we reviewed earlier. The fact is that they have two cables at once, which are designed to synchronize the device with a personal computer or laptop. The first cable is 79 centimeters long. The second one is shorter by 70 cm. The body has an end where you can hide a short wire. Also, the series hard drives use a USB 3.0 A type socket. All models described earlier use USB 3.0 Micro-B. Weighing 270 grams, the series' hard drives measure 139.45 mm x 94 mm x 18.1 mm.

TOSHIBA Stor.E Basics

The casing of this line of external memory drives is made of matte black plastic. There are four legs at the bottom of the gadget, which simply pleases. But as for the volume, here the series may not please all users. The maximum amount of non-volatile memory that is available in these drives is 1 terabyte. The other two modifications of the series have, respectively, volumes of 500 GB and 750 GB.

The USB 3.0 cable is neither short nor long. Its length is 52.5 centimeters. It is interesting that the models of the series differ in size. The version of the hard drive, which has a capacity of 1 TB, is represented by a mass of 180 grams and a thickness of 16.5 centimeters. At the same time, the rest of the models will be thinner and smaller in terms of weight: their height is only 13.5 millimeters, and their weight is 150 grams.

Transcend StoreJet 25H3

External discs of this brand have a casing, which is covered with a rubber layer. Thus, the manufacturer has worried about the mechanical strength by adapting the external hard drives of this series to unexpected mechanical shock and stress. The models in the line have 500 gigabytes of memory, as well as 1 and 2 TB. If we talk about the color scheme, then the hard drives of the series are available in purple-black, as well as in blue. The length of the cable for synchronization with a PC is about 45 centimeters.

A distinctive feature of this lineup is that there is a button on the body that serves for quick reconnection. It helps to activate the special mode. There is no need to unplug and unplug the hard drive and then sync it back to your computer. Weighing 216 grams, the 500 GB and 1 TB versions of the drive have the following dimensions: length - 131.8 mm, width - 80.8 mm, and thickness - 19 millimeters. The model, which is designed for 2 terabytes of internal memory, is slightly thicker (24.5 mm) and weighs a little more (284 grams).

Western Digital My Passport Ultra

Like almost all other models, the series range of this external hard drive is made of matte black plastic. There are four legs on the bottom that will save the device from vibration during operation. The cover of the hard drive, depending on its modification, can be of a different color. Currently available in black, blue, red and metallic colors.

The amount of built-in memory is standard: 500 gigabytes, 1 TB or 2 TB. The USB cable does not fold anywhere; its length is 46 centimeters. A special bag made of velvet is provided for transportation. Weight (depending on the model) varies from 130 to 230 grams. Dimensions also vary. Length can be from 110 to 110.5 millimeters, width - from 81.6 to 82 millimeters. This is not so noticeable, but how the thickness of the hard disk grows with the increase in its memory capacity is seen quite well. It falls in the range from 12.8 to 20.9 millimeters.

A data storage device is a device on which all computer data is stored. In addition to the drive, this device is called a hard drive or hard drive. A hard disk differs from a conventional "floppy" disk, or in other words, a floppy disk, in that information is recorded on hard plates made of aluminum or ceramics, and on top they are covered with a ferrimagnetic material. Hard drives are equipped with one or more platters on the axle.

The data storage device (HDD) includes a sealed unit and an electronic board. The sealed unit is filled with ordinary dust-free air by atmospheric pressure, and all mechanical parts are included in its equipment. The kinematics of the data accumulator includes one or more magnetic disks, which are rigidly fixed to the motor spindle, as well as a system responsible for positioning the magnetic heads. The magnetic head takes place on one of the sides of a moving magnetic disk and its functional duties include reading and writing data from the rotating surface of the magnetic disk. The heads themselves are attached with special holders, and their movement is carried out using a positioning system between the edge and the center of the disc. It is possible to achieve accurate positioning of the magnetic heads by means of servo information recorded on the disc. The positioning system, by reading this information, is able to determine the strength of the current passed through the coil of the electromagnetic wire so that the magnetic head can be fixed over the required track.

After the power is turned on, the processor of the hard drive (drive) begins to test the electronics, after which a command is issued in order to carry out the process of directly turning on the spindle motor. As soon as the initialization is completed, the positioning system is tested, during which the tracks are searched, in given sequence... In case the testing went well, the hard drive sends a signal that it is ready to work. To increase the level of reliability of storing computer information, hard disks (drives) are equipped with a special firmware that monitors the technological parameters available for the reading and analysis program. If the computer is threatened with a failure, then with the help of this program, the user will find out about it in a timely manner.

In addition, the data storage is also a hybrid hard disk, which consists of a traditional hard disk equipped with additional flash memory. This flash memory is completely non-volatile and plays the role of a buffer that stores the most frequently used data. As a result of the activity of this device, access to the magnetic disk is reduced, which accordingly leads to a decrease in power consumption. The level of reliability of information storage also increases, the time required for loading and for bringing the system out of sleep mode decreases, as well as the temperature and acoustic noise that the hard disk emits is significantly reduced.

The device of all hard drives is completely similar and absolutely all types of data storage devices can fail, therefore, the main thing that every user must remember is that in order for a hard drive to be as reliable as possible in use, it must be properly operated. Namely, to protect against overheating, shock, increased vibration of the case, frequent switching on or off. In addition, you do not need to use a power supply that is of poor quality.

In most laptops, you cannot insert a second hard drive, and changing the main one is not always easy. External storage devices come to the rescue.

For storing, transferring and backing up data in computer systems, external drives are used. The main types of such drives are devices based on hard drives and flash memory. In some cases, external optical disc drives are used as such drives, however, since most computers have internal drives for reading and writing CD, DVD or Blu-ray, such drives are of limited distribution and we will not dwell on them here (more about optical drives, see separate material).

Flash drives

With the price drop for flash memory, external drives based on it are becoming more common. A typical flash drive is a small, disposable lighter-sized device with a built-in USB connector... At the same time, the volume of such miniature drives can vary in a very wide range: from one to 128 GB. To date, the most popular models with a capacity of 8 to 16 GB can be purchased for 500-900 rubles, modifications in protected rubberized and sealed aluminum cases are slightly more expensive. As a rule, 8-16 gigabyte flash drives are purchased not for storage and backup, but for online data transfer.

High-capacity flash drives are significantly more expensive: 64 GB models are already estimated at about 5,000 rubles, and 128 GB models - at 11,000 rubles and more. It is easy to calculate that the cost of a gigabyte of disk space in such drives is about one and a half times higher (from 85 rubles) than in drives of small capacity. In addition, an external mini-hard drive of the same volume will cost about three times cheaper, so consumers prefer them.

External HDs

Hard drives have been the optimal solution for storing and backing up large amounts of data for decades. Modern hard drives are distinguished by high reliability, large capacity and low cost of data storage: in the best models, it ranges from 3 to 4 rubles per gigabyte.

External hard drives can be divided into four broad categories: 2.5-inch drives, 3.5-inch drives, multimedia drives, and NAS systems.

Drives based on 2.5-inch "notebook" hard drives are the smallest: they are considered portable and easily fit into a shirt pocket. However, compared to 3.5-inch disks, they have significantly lower write and read speeds, limited capacity, and the cost of a gigabyte of storage is one and a half to two times higher. The typical read speed for such disks is 35 MB / s, the write speed is 30 MB / s, the best models have read and write speeds up to 50 MB / s.

The volume of 2.5-inch external hard drives is from 120 to 500 GB, the cost of storing a gigabyte of data is, on average, from 8 to 12 rubles.

As a rule, 2.5-inch hard drives are equipped with a USB 2.0 interface, sometimes eSATA and almost never support FireWire, with the exception of drives under the ZIV brand. In many cases, USB power is sufficient for these drives.

It is also worth mentioning models based on 1.8-inch "subnotebook" hard drives, which are even smaller than 2.5-inch ones. Usually the capacity of such drives is limited to 120 GB and they are equipped exclusively with a USB 2.0 interface. These discs are rarely found in stores; they are usually handed out at various events as souvenirs.

The most massive and demanded category is external drives based on standard 3.5-inch hard drives. They can consist of one or two hard drives located in the same case, and in the latter case, the possibility of organizing RAID arrays of levels 0 (combining disks) and 1 (mirroring) is usually provided.

For drives based on 3.5-inch hard drives, a read speed of 70-90 MB / s and a write speed of 60-80 MB / s are typical. The most productive models can read speeds up to 120 MB / s, and write speeds up to 110 MB / s. The volume of such drives is usually from 500 GB to 2 TB in single-drive models and up to 4 TB in dual-drive models. The cost of storing one gigabyte, on average, is from 4 to 8 rubles, for best models- from 3 to 4 rubles.

3.5-inch external drives can be equipped with a full range of a wide variety of modern interfaces: in addition to the mandatory USB 2.0, they install eSATA, FireWire 400 and FireWire 800 controllers, as well as the promising USB 3.0 interface.

Multimedia drives are a special category of external hard drives based on 2.5- or 3.5-inch hard drives, which are equipped with a built-in decoder for popular audio and video formats, as well as a software media player with hardware controls. Essentially, these drives are hard drive-based media players and usually come with a remote control.

Such devices can be directly connected to a TV and audio system and they will act as a stand-alone multimedia player not connected to a computer. To do this, they are equipped with "consumer" video interfaces (composite, component, HDMI), as well as analog and digital audio outputs. In many cases, a card reader is built into these devices, which allows direct playback of multimedia content from removable flash cards. There are modifications designed exclusively for connecting removable hard drives, purchased separately.

The standard arsenal of multimedia drives is support for MPEG-1/2/4, DivX and XviD video formats, MP3, WAV, AAC audio formats, and JPEG digital images. The possibility of working with other formats should be specified separately when choosing each specific model.

At the same time, of course, such devices can also be used as ordinary computer external drives - usually via USB 2.0 and eSATA interfaces.

The most complex and expensive type of external storage is NAS systems, that is, networked storage. These are external devices with one or more 3.5-inch hard drives, equipped with an Ethernet network interface (all modern models have gigabit ones) and having the functionality of a mini-server.

3. Optical technologies

3.1 CDs

3.2 DVD media

Conclusion

Bibliography

2. Types of magnetic media

2.1 Floppy disks

The diskette consists of a round polymeric substrate coated on both sides with a magnetic oxide and placed in a plastic bag, on the inner surface of which a cleaning coating is applied. Radial slots are made on both sides of the package through which the read / write heads of the drive gain access to the disc.

Floppy disks of each standard size are usually double-sided. Single track density is 48 tpi (tracks per inch), double density is 96 tpi, and high density is usually 135 tpi.

When the 3.5 "disc is inserted into the unit, the protective metal flap is pulled back, the drive spindle enters the middle hole and the side pin of the drive fits into the adjacent rectangular positioning hole. The motor rotates the disc at 300 rpm.

Disk drives for floppy disks use so-called "open loop tracking", they do not actually search for tracks, but simply set the head in the "correct" position. In hard disks, by contrast, servo motors use heads to check positioning, which allows recording at a lateral density many hundreds of times higher than is possible on a floppy disk.

The head is moved by a lead screw, which in turn is driven by a stepper motor, and when the screw rotates through a certain angle, the head travels a set distance. The density of data recording on a floppy disk is limited by the accuracy of the stepper motor, in particular, this means 135 tpi for 1.44 MB floppy disks. The disk has four sensors: disk motor; write protection; the presence of a disk; and track sensor 00.

2.2 External drives on hard drives

In recent years, technologies have spread for placing standard hard disk drives in a mobile (portable) external case (box), which is connected to a computer via an external interface.

Since today the capacity of a hard disk drive is measured in gigabytes, and the size of multimedia and graphic files is tens of megabytes, the capacity from 100 to 150 MB is quite sufficient for the medium to occupy the traditional niche of floppy disk drives - moving several files between users, archiving or backup individual files or directories and sending files by mail. A number of devices are offered in this range for the next generations floppy disks which use flexible magnetic media and traditional magnetic storage technology.

Zi p-drives... Without a doubt, the most popular device in this category is the ZipIomega floppy drive, first released in 1995. The high efficiency of Zip drives is ensured, firstly, by their high rotational speed (3000 rpm), and secondly, by technology proposed by Iomega (which based on the Bernoulli aerodynamic effect), while the floppy disk "sticks" to the read / write head, and not vice versa, as in a hard disk drive. Zip drives are soft, like floppy drives, making them cheaper and less susceptible to shock.

Zip drives have a capacity of 94 MB and are available in both internal and external versions. Internal modules correspond to the 3.5 "form factor, use the SCSI or ATAPI interface, the average seek time is 29 ms, the data transfer rate is 1.4 KB / s.

Superdisks. The range from 200 to 300 MB is best suited to the concept of superdisk territory. The capacity of such devices is 2 times higher than that of a replacement floppy disk drive, and is more typical for a hard disk drive than for a floppy disk. Devices in this group use magnetic or magneto-optical technology.

In 2001, Matsushita announced the FD32MB technology, which gives the option of high-density formatting of a regular 1.44MB HB floppy disk to provide storage capacity of up to 32MB of disk space. The technology is to increase the recording density of each track on an HD floppy disk using a superdisk magnetic head for reading and a conventional magnetic head for writing data. While a conventional floppy disk holds 80 circular data tracks, the FD32MB increases this number to 777. At the same time, the track feed from 187.5 µm for an HD diskette decreases to about 18.8 µm.

Removable hard drives... The following capacity range (from 500 MB to 1 GB) is sufficient for backing up or archiving a disk partition (partition) of a reasonably large size.

In the range over 1 GB, removable disk technology is borrowed from conventional hard disk drives. Released in mid-1996, the IomegaJaz drive (1 GB removable hard drive) was hailed as an innovative product. When Jaz hit the market, it immediately became clear where to use it - users were able to create audio and video presentations and transfer between computers. In addition, such presentations could be launched directly from the Jaz media, without the need to rewrite the data on a hard drive.

Flash memory... Apart from magnetic media, flash memory works simultaneously like RAM and hard disk drives. It resembles ordinary memory, in the form of discrete chips, modules, or memory cards, where, like in DRAM and SRAM, data bits are stored in memory cells. However, just like a hard disk drive, flash memory is non-volatile and retains data even when the power is turned off.

ETOX technology is the dominant flash technology, accounting for about 70% of the total non-volatile memory market. Data is entered into flash memory bit by bit, byte by byte, or in words using an operation called programming.

Although electronic flash drives are small, fast, consume little power, and can withstand shocks up to 2000g without destroying data, their limited capacity makes them an inappropriate alternative to a PC hard drive.

3. Optical technologies

3.1 CDs

In the beginning, CDs were used exclusively in high-quality sound-reproducing equipment, replacing outdated vinyl records and tape cassettes. Soon, however, laser disks began to be used on personal computers. The computer laser discs have been called CD-ROMs. In the late 90s. the device for working with CD-ROM has become a standard component of any personal computer, and the vast majority of programs began to be distributed on CD-ROMs.

Compact disc drive (CD-ROM) - Reading information from a CD is done using a laser beam of lower power. The servomotor, on command from the internal microprocessor of the drive, moves the reflective mirror or prism. This allows the laser beam to be focused on a specific track. The laser emits coherent light consisting of synchronized waves of the same length. The beam, hitting the light reflecting surface (area), is deflected through the splitting prism to the photodetector, which interprets it as "1", and falling into the depression (pit), is scattered and absorbed - the photodetector fixes "0".

While magnetic disks rotate at a constant rpm, that is, at a constant angular velocity, a compact disk usually rotates at a variable angular velocity to provide a constant linear velocity when reading. Thus, the reading of internal tracks is carried out with an increased number of revolutions, and external ones - with a reduced number of revolutions. This is the reason for the lower speed of access to data for CDs in comparison with hard drives.

3.2 Media DVD

A universal digital disc (digitalversatiledisc-DVD) is a type of storage device that, unlike CDs, since its launch on the market has been designed for widespread use in both the audio-video and computer industries. DVD discs, which are the same size as standard CDs (diameter 120 mm, thickness 1.2 mm), provide up to 17 GB of memory at transfer rates faster than CD-ROMs, and have CD-ROM-like access times. and are divided into four versions:

DVD-5 - 4.7GB, single-sided, single-layer disc;

DVD-9 - 8.5 GB single-sided, dual-layer disc;

DVD-10 - 9.4GB Double Sided Single Layer Disc;

DVD-18 - Up to 17GB capacity on double-sided, dual-layer disc.

DVD - ROM... As with the discs themselves, there is little difference between DVD and CD-ROM drives, as the only obvious thing is the DVD logo on the front panel. The main difference is that CD-ROM data is written close to the top layer of the disc surface, and the data layer for DVD is closer to the middle so that the disc can be double-sided. Therefore, the optical read unit of a DVD-ROM drive is more complex than its CD-ROM counterpart to make it possible to read either one or the other of these types of media.

One of the earliest solutions was to use a pair of swivel lenses, one to focus the beam at the DVD data levels and the other to read conventional CDs. More sophisticated designs have since emerged that obviate the need for lens switching. For example, Sony's "dual discrete optical sampling" has separate lasers optimized for CD (780 nm) and DVD (650 nm). Panasonic devices switch laser beams using a holographic optical element capable of focusing the beam at two different discrete points.

DVD-ROM drives rotate much more slowly than their CD-ROM counterparts. However, since the data on DVD is packed much more densely, its performance is significantly higher than that of a CD-ROM at the same rotational speed. While a regular audio CD-ROM (lx or one-shot) has a maximum data transfer rate of 150 KB / s, a DVD (1x) can transfer data at 1250 KB / s, which is only achieved at eight times (8x) the speed of a CD-ROM drive. ...

There is no universally accepted terminology to describe the various “generations” of DVD drives. However, the term "second generation" (or DVDII) usually refers to 2x drives that are also capable of reading CD-R / CD-RW media, while the term "third generation" (or DVDIII) usually refers to 5x (or sometimes 4x) drives. , 8x, or 6x), some of which are capable of reading DVD-RAM media.

Recordable disc formats DVD

There are several versions of recordable DVD:

DVD-R Ordinary, or DVD-R;

DVD-RAM (rewritable);

Writable DVD . DVD-R (or Recordable DVD) is in many ways similar in concept to CD-R - it is a write-once media that can contain any type of information commonly stored on mass-produced DVDs - video, audio, pictures, data files, programs, multimedia, etc. Depending on the type of content being recorded, DVD-R discs can be used on virtually any compatible DVD playback device, including DVD-ROM drives and DVD-Video players. Since the DVD format supports double-sided discs, up to 9.4 GB can be stored on a double-sided DVD-R disc... Data can be written to DVD at 1x speed (11.08 Mbps, which is roughly equivalent to 9x CD-ROM speed). Once burned, DVD-R discs can be read at the same speeds as mass-replicated discs, depending on the x-factor (multiplicity of speed) of the DVD-ROM drive used.

DVD-R, like CD-R, uses constant linear velocity (CLV) to maximize the recording density on the disc surface. This requires a change in revolutions per minute (rpm) as the diameter of the track changes as you move from one edge of the disc to the other. The recording starts on the inside and ends on the outside. At 1x speed, the rotational speed varies from 1623 to 632 rpm for a 3.95 GB disk and from 1475 to 575 rpm for a 4.7 GB disk, depending on the position of the record / playback head on the surface. For a 3.95 GB disc, the track spacing (feed), or the distance from the center of one turn of the spiral track to the adjacent part of the track, is 0.8 microns (microns), which is half that of CD-Rs. The 4.7 GB disc uses an even lower track feed - 0.74 microns.

DVD - RAM . The rewritable DVD-ROM or DVD-RAM uses phase change technology, which is not a pure optical technology of CD and DVD, but a combination of some features of magneto-optical methods and originates from optical disk systems. The applied landgroove format makes it possible to record signals both on the grooves formed on the disc and in the spaces between the grooves. Recesses and sector headers are formed on the surface of the disc during its casting.

In mid-1998, the first generation of reusable DVD-RAM products with 2.6 GB capacity on both sides of the disc appeared. However, these early devices are incompatible with higher capacity standards that use an expansion contrast layer and a thermal buffer layer to achieve higher recording densities. The specification for version 2.0 DVD-RAM with a capacity of 4.7 GB on one side was released in October 1999.

DVD - RW . Formerly known as DVD-R / W or DVD-ER, DVD-RW media (which became available in late 1999) emerges as Pioneer's evolutionary development of existing CD-RW / DVD-R technologies.

DVD discs-RW use the technology of changing the phase state of a substance to read, write and erase information. A 650 nm laser beam heats the sensitive alloy layer to either crystalline (reflective) or amorphous (dark, non-reflective) depending on the temperature level and subsequent cooling rate. The resulting difference between the recorded dark marks and the erased reflective marks is recognized by the player or disk drive and allows the stored information to be played back.

DVD-RW media use the same physical addressing scheme as DVD-R media. During the recording process, the laser of the drive follows the microscopic recess, recording data in a spiral track.

One of the main advantages of the third rewritable DVD-DVD + RW format is that it offers better compatibility than any of its competitors.

DVD + RW . The DVD-RAM specification was a compromise between two different offerings from major competitors - the Hitachi, Matsushita Electric and Toshiba grouping on the one hand, and the Sony / Philips alliance on the other.

DVD + RW shares many similarities with competing DVD-RW technology in that it uses phase change media and assumes the user experience of CD-RW discs. In DVD + RW format, discs can be recorded in both constant linear velocity (CLV) mode for sequential video recording, and constant angular velocity (CAV) format for direct access.

DVD + R . The DVD + R Dual Layer System uses two thin organic films of paintable material separated by a spacer (filler). Heating by a concentrated laser beam irreversibly changes the physical and chemical structure of each layer so that the altered areas acquire optical properties that are different from the original ones. This causes reflectivity to fluctuate when the disc is rotated and produces a read signal the same as stamped DVD-ROM discs.

Conclusion

Thus, the following generalizing conclusions can be drawn:

1. Magnetic drives are the most important medium for storing information in a computer and are divided into magnetic tape drives (LMT) and magnetic disk drives (LMD).

2. Magnetic disks are used as storage devices that allow you to store information for a long time, when the power is off.

3. The main types of drives: floppy disk drives (floppy disk drives); hard disk drives (HDD); magnetic tape drives (NML); drives CD-ROM, CD-RW, DVD.

4. The main types of media: floppy disks; hard magnetic disks (Hard Disk); cassettes for streamers and other NML; CD-ROMs, CD-R, CD-RW, DVD.

5. There are several versions of recordable DVD: DVD-R ordinary, or DVD-R; DVD-RAM (rewritable); DVD-RW; DVD + RW.

Bibliography

1. Golitsyna O. L., Popov I. I. Fundamentals of algorithmization and programming: textbook. allowance. M .: FORUM: INFRA-M, 2002.

2. Information technologies: textbook. allowance / O. L. Golitsyna, N. V. Maksimov, T. L. Partyka, I. I. Popov. M .: FORUM: INFRA-M, 2006.

3.Kaymin V.A. Informatics: textbook. M .: INFRA-M, 2000.

4. Maksimov N. V., Partyka T. L., Popov I. I. Architecture of computers and computing systems: textbook. allowance. M .: FORUM: INFRA-M, 2004.

5. Maksimov N. V., Partyka T. L., Popov I. I. Technical means of informatization: textbook. allowance. M .: FORUM: INFRA-M, 2005.

6. Maksimov N. V., Popov I. I. Computer networks: textbook. allowance. M .: FORUM: INFRA-M, 2003.

7.Nadtochy A.I. Technical means of informatization: textbook. allowance / Under total. ed. K.I. Kurbakov. M .: KOS-INF; Grew up. econom. acad., 2003.

8. Fundamentals of Informatics (textbook for applicants to economic universities) / K. I. Kurbakov, T. L. Partyka, I. I. Popov, V. P. Romanov. M .: Exam, 2004.

9.Partyka G.L., Popov I.I. tutorial... - M .: FORUM: INFRA-M, 2007.

10. Smirnov Yu.P. History of computer technology: Formation and development: textbook. allowance. Publishing house of Chuvash, un-that, 2004.

Storage devices and information carriers. Information storage device - a device that reads and / or writes information. Information storage devices are: · internal and external: · with removable and ...

Storage devices and information carriers.

Information storage device - a device that reads and / or writes information.

Information storage devices are:

· internal and external:

· with removable and non-removable media;

· stationary and portable.

Internal drives are located in the PC system unit and are connected to special connectors on the motherboard.

External and portable drives are housed in their own case and are connected to a computer via standard I / O ports. External storage devices are used for backing up and storing information, as well as for transporting data from one computer to another.

Information carrier Is a device on which information is directly recorded (stored), for example, a disk, a cassette with a magnetic tape, etc.

The drive and the storage medium can be made in one housing, i.e. compose one whole, for example, a hard disk HDD (fig. 13).

Rice. 13. Hard disk drive HDD

The drive can have removable media, for example:

At the FDD drive removable media - floppy disk ( Floppy disk);

DVD-RW drive (fig. 14) removable storage medium - DVD disc.

Rice. 14. DVD-RW drive

In some cases, the division into drive and media is arbitrary. For example, the internal storage of information, random access memory ( RAM ) and portable storage FLASH - the card is both a storage device and an information carrier.

Basic storage and storage media

Storage device	Russian designation	International designation	Drive type	Carrier	Media type
RAM			interior	she
Persistent memory		ROM BIOS	interior	she
Hard disk HDD (hard disk drive)			interior	HDD	non-removable built-in
FDD drive (floppy disk drive)			interior	floppy disk	removable portable
CD -ROM, CD -RW - drive for reading and writing CD-disks		CD-ROM CD-RW	interior	CD disc (compact disc)	removable portable
DVD -RW - drive for reading and writing CD and DVD-disks		DVD-R DVD-RW	interior	DVD disc	removable portable
FLASH card		FLASH	external, portable	she

The main characteristic of a medium (drive) is its capacity, i.e. the maximum amount of information that can be recorded on this device. Storage capacity is measured in the following units:

	designation	International designation
kilobyte
megabyte
gigabyte

Recently floppy disks and CDs -disks are outdated, in the near future they will cease to be used and are actively replaced by more capacious media FLASH -cards (fig. 15) and DVD discs.

Rice. 15 .. FLASH -card

The capacity of the main storage media.

Media / storage		Note
Removable storage media
Floppy disk or floppy disk	1.44 Mb	go out of use
CD disc	650 Mb, 700 Mb	go out of use
DVD disc	4.7 Gb, 9 Gb	DVD discs can be single-sided or double-sided, single-layer and double-layer
FLASH card	256 Mb, 512 Mb, 1 Gb, 2 Gb
Internal media / storage media
RAM memory	512 Mb 1 Gb	standard for Windows XP standard for Windows Vista
Hard disk HDD	120 - 300 Gb	Typical HDD capacity of a modern PC

External data storage devices appeared a very long time ago, in fact, at the dawn of the computer era, all data storage devices were external. This approach to connectivity was largely due to the storage technology used at the time and the general level of development of the semiconductor industry. However, over time, data storage devices have moved into the cute and compact cases of personal computers (PCs).

Progress is progress, miniaturization is reaching new and new heights. Nevertheless, for some tasks there is still a need for external data storage devices. For example: a designer who has to transfer large files the customer or there is a need to work with this material at home. Again, it may be necessary absolute protection his information from unauthorized access: he disconnected the disk and took it with him - as they say, absolute protection :).

Below I will consider the main ways of connecting external data storage devices and their characteristic features - a kind of historical tour.

Bare interface

Initially, the only way to connect an external storage device to a PC was to use the SCSI interface. It is worth noting that in the SCSI interface the ability to connect not only data storage devices, but also all kinds of external peripherals was implemented. For the first time I had a chance to come across external data storage devices on the example of a hard disk and CD-ROM with SCSI interface back in 1992. The disc and CD-ROM were convenient and not very large boxes that could be disconnected from one PC and quickly connected to another PC without disassembling them. Well, if the operating system was perfect enough, then it could be done in "hot" mode. Classical appearance a similar case can be seen in the photo.

True, for such a connection method, it was required that both machines had a SCSI interface, and this pleasure at that time cost a lot of money. However, for some tasks, this ability to quickly transfer and connect large storage media was simply invaluable. As an interface, SCSI had and still has tremendous capabilities, but they are all squeezed into a rigid framework of high prices. However, this connection method has other disadvantages as well. Perhaps the main ones are the use of thick and bulky 50-wire patch cables and the low prevalence of the SCSI interface. The photo shows SCSI and USB interface cables for comparison.

The IDE interface, which began its triumphant march across the PC market a little later, was very primitive in its capabilities, but had a huge advantage over SCSI - it was very cheap. But the old rule that “cheap doesn't mean good” hasn't stopped working. The wider the IDE interface spread to the PC, the more acute the need arose to implement such functions that SCSI already possessed, including the ability to use IDE to connect external storage media. The industry has taken the shortest path to solving this problem. We are talking, as you guessed it, about the so-called Mobile Rack devices. This is a primitive basket that houses a hard drive and a socket, which is usually installed in a 5-inch slot on the front of a PC.

All this design allows you to connect / disconnect the hard drive without disassembling the computer. Calling this method of connecting data storage devices is not an "external" language, however, fishlessness and cancer are fish, although it is not very convenient, but cheap. Moreover, for a very narrow range of tasks, this method is almost ideal. Over time, the capabilities provided by new operating systems have even made it possible to implement the primitive hot-swappable IDE drives. But too frequent cases of disk failure with such a connection severely limit both the scope of this method and the number of users who want to risk their hardware. In addition, baskets from Mobile Rack, made by different companies, were often physically incompatible with the slots due to the non-standard arrangement of the connectors. However, the Mobile Rack connection method is still alive and well.

But let's go back a little. The possibilities that the primitive Mobile Rack provided, of course, could not fully satisfy the users, and the computer industry once again launched an evolutionary process.

Building bridges

So, the industry had to evolve within the framework of certain requirements for external data storage.

Devices must be hot plug / unplugable
It is necessary to use existing technologies
The solution must be cheap and widespread

As usual, the designers went the simplest way. What does each computer have and is worth a penny? That's right, any computer has a port like LPT! Of course, it is not fast, and it is not very convenient to work with it, but what we have is what we proceed from. From that moment on, a class of devices called bridges emerged on the data storage market. Bridges are hardware and software systems that allow a computer to work with an external IDE or SCSI storage device using a peripheral bus or interface.

In the following, I will mainly use the IDE device examples as it is more common. But everything that will be said about IDE can just as well be said about SCSI, since the ideology remains the same regardless of the interface.

This approach - using the LPT interface - was certainly not ideal, but it worked nonetheless. So, what the user was able to get in the end.

Ability to connect external storage devices to any PC.
No need to upgrade your computer.
Cheapness.
Easy to connect.

Low speed, several orders of magnitude lower than that of SCSI or IDE (with a direct connection).
The need to install drivers.
A primitive set of commands and capabilities.

Well, the first pancake always comes out lumpy. However, what matters to us is that the industry has put bridge technology into practice for the first time. This was the first step in the development of a whole class of similar devices.

However, as time went on, the capacities of hard disks grew, the volumes of data grew. The speed provided by the LPT interface has become sorely lacking. The industry is looking for new connectivity options for faster, larger storage devices.

The idea of connecting devices through bridges began to develop in new directions. By that time, almost all more or less modern computers were equipped with such a peripheral data transfer bus as USB. Although USB was the most common bus, it turned out to be the most unclaimed at that time. A fairly promising development, integrated by INTEL into its chipsets and therefore practically worthless, it was present at many motherboards, but the lack of devices that could work with this bus turned it into a beautiful toy. Now the hour has struck. In fact, USB was designed as a peripheral bus for connecting computer peripherals outside of the machine case using the plug "n" play standard. The old man LPT simply could not resist such pressure. So, what users could get when switching from LPT-IDE bridge to USB-IDE bridge.

Significant increase in speed. USB - 750-950 Kb / s versus 250-300 Kb / s for LPT
Perfect hot plug / unplug capability.
No hassle in setup, completely P&P.
Convenient cables for connection.

It was impossible to pass by such an opportunity to use USB, and users received a whole range of IDE devices capable of working over USB 1.1. Here are some examples.

USB-IDE bridge board - as they say, "DIY" constructor. The user can easily alter any existing external storage enclosure if desired.

External enclosure for 3-inch hard drive.

External enclosure for a 2-inch hard drive, with some models of hard drives it is even possible to work without an external power supply.

Integration is a curious process

A small lyrical digression. Despite the fact that the methods of connecting drives using a bare interface and using a bridge have cardinal differences, the market is a market, and if there are unoccupied niches in it, then they should be occupied. Apparently, guided by such motives, some companies have developed such curious combi devices that can work in different guises.

Allows you to work in two modes: as a universal Mobile Rack for computer devices, and as an external device connected using a USB bridge. In the first case, you have the opportunity to quickly remove the data carrier from the computer without disassembling it, and in the second case, you can easily connect the removed medium to any computer that does not have a slot for the Mobile Rack, but has a USB bus.

The bridge must be wide!

Agree, it's a shame to have a hard drive capable, for example, of transferring 20 Mb / s, and connecting it via a USB bridge at a speed of 900Kb / s. Not everyone will have the patience, say, to rewrite 10 GB of information at this speed. Faced with such problems, the computer industry turned to the FireWire (IEEE 1394) peripheral data bus, which came to the PC world from the world MAC computers... Possessing outstanding characteristics and capabilities, this bus was initially not widely used in the world due to the policy of the developer Apple. And what a chance Apple had to become a leader in this area! However, if there is a need for speed, then it is necessary to somehow satisfy it. Incidentally, the industry's decision to use FireWire in this way has had a positive impact on the cost of FireWire devices. During the year, their price decreased by more than three times. When migrating from USB 1.1 to FireWire, users experienced the following key benefits.

Increase the maximum transfer rate from 10 MBit / s (USB) to 400 MBit / s (FireWire).
The ability to power external devices from the 1.25A / 12V bus (FireWire) against the maximum 500 mA / 5V (USB).

Again, a small example. Here is a case for a 2 "hard drive.

However, unlike USB, the user does not have to puzzle over how to find a suitable hard drive that will work without additional power. Power is taken directly from the bus (1.25A 12V = 15W), and therefore absolutely any hard drive will do.

However, progress does not stand still, and clouds hang over FireWire in the form of USB 2.0. Possessing somewhat better characteristics, it is capable of becoming its serious competitor. The main bargaining chips in the fight were to increase the speed from 10 MBit / s to 480 MBit / s and support for all old USB 1.1 devices. True, when USB 2.0 is introduced to the market, politics causes some bewilderment. Intel... Previously, the corporation was very active in promoting this bus, but contrary to the expectations of users, it did not integrate it into its latest i845D and i850 chipsets. Why this did not happen remains a mystery. However, there is already everything you need for widespread adoption of USB 2.0 in the PC market. Firstly, the market is more than provided with chips for creating expansion cards to support USB 2.0, and secondly, external storage devices that use USB 2.0-IDE bridges are being actively promoted on the market.

Here, for example, is a bridge on a chip from In-System. It is designed in such a way that it can very easily replace the previous generation bridge (photo just above in the text). And that's not all, the pricing policy of the company is such that the cost of the USB 2.0 bridge is almost equal to the cost of the previous USB 1.1 model.

Bridge to bridge strife

The market is the market, and if there is demand, then everyone who can try to get into this niche in the market. Therefore, it is not surprising that a natural process of competition was observed in this market segment as well. As usual, competing firms presented their products one after another. From here we get some differences in transmission speed for practically similar products, but using bridges from different companies.

For USB 1.1, this difference was not so fatal due to the low transfer rate. The values of the maximum possible transfer rate, as a rule, fluctuated in the range of 750-950 Kb / s. However, the 20% difference looks quite large.

The situation on the market of high-speed IDE-FireWire bridges turned out to be much more interesting. Here the maximum speed could differ several times. Moreover, I observed such a difference in devices of the same company, assembled on different chips of FireWire-IDE bridges. Curiously, both chips were from the same manufacturer. Below you can take a look at the comparison results.

Chip Oxford semi. OXFW910

Chip Oxford semi. OXFW911

Well, is the difference impressive? I can understand those who, for example, need to connect a CD-RW recorder through a similar bridge. By and large, they will not give a damn about speed, but what about those who want to connect a modern high-speed hard drive? So that being said, be careful when choosing such a device for yourself. Below I will give the test data of some of the most commonly used chips, on the basis of which IDE-FireWire bridges are built. Data obtained from Skymaster. This company is engaged in the production of all kinds of USB and FireWire devices. An IBM DTLA-307020 hard drive was used as a test device; testing was carried out under OS Windows 2000.

Unfortunately, it is not yet possible to compare at least two USB 2.0-IDE bridges, since at the moment such devices are supplied to the market only by In-System. But recently, two more large firms - NEC and ALI - announced similar devices, so let's see what they get and try to compare them in the future.

Bridges of all countries, unite!

In one place you have FireWire, in the other - only USB, and so you want, for example, to bring your friend a couple of new films in DVD format, but copied to a hard drive. However, you have a FireWire drive, and your friend only has USB 1.1, well, he can't get him a FireWire controller for that. Well, the controller can and should be started, especially since peripheral manufacturers have long hinted at the need for all widely used peripheral buses in every computer. Just take a look at this universal hub, isn't it cute and practical?

But this card can make you happy with two high-speed buses at once - USB 2.0 and FireWire.

Well, universality is sacred, the manufacturers decided and, without hesitation, set about developing bridges with combined interfaces. In principle, the main difficulty is to compactly place everything on the bridge board. necessary components and try to ensure that the cost of such a device is not too high. The first birdie was such a FireWire / USB1.1 - IDE bridge.

And this is just the beginning, as the FireWire / USB2.0 -IDE versions are ready and will soon be launched. This is where the user can afford to forget about the compatibility of his external storage with computers, since the computer has some kind of peripheral bus for sure :).

Bridges, you say ... well, well

This year saw the final release of the Serial ATA interface. And although so far it is intended only to replace the outdated IDE, it already has the manners of Napoleon. Judge for yourself, this interface is practically similar in its functions to both FireWire and USB 2.0 devices, but at the same time it is even faster. Serial ATA data transfer rates can be up to 150 Mb / s. Of course, it will take some time before it hits the market in all its glory. Although for the time being it is positioned exclusively as an internal interface, it nevertheless has all the makings of an interface for connecting external devices. See for yourself, the interface uses a star topology to connect devices. So you can remove one or two connectors for connecting external devices without any problems, and the devices will function similarly to the internal ones. The maximum cable length is 1 meter - this is also quite enough for connecting most external devices.

The cable consists of two pairs of data wires and three ground wires, so the cable is very compact and convenient. Of course, the future will show whether this interface will invade the external storage market or not, but this possibility must be borne in mind.

Every user at least once in his life has heard of such a category of devices as external storage devices. However, not everyone had the opportunity to work with them or touch them by touch. And those users who have worked with some external data storage devices do not have a special idea about what types of these devices exist today, as well as about the main characteristics that each type of these gadgets possesses. Nevertheless, external storage devices are very convenient, practical to use and provide users with great opportunities, so it is necessary to get acquainted with them in more detail.

The purpose

Any electronic device, which can be found on store shelves, is designed to perform specific tasks. External data storage devices are no exception and allow you to store large amounts of information in electronic form, which can be stored undamaged for a long period of time. However, for this, external drives must have a sufficient amount of memory that would allow recording large data packets, and also have high reliability so that information does not disappear from the device's memory.
Among the main technical characteristics of external data storage devices that you need to pay attention to when buying a device are:
- read / write speed, on which the speed of the device depends;
- the quality of the components from which the gadget was made;
- availability of data encryption function, significantly increasing the level of protection of confidential information stored on the drive;
- compatibility, on which the ability to synchronize external drives with other devices and operating systems depends.

However, it should be noted right away that it is impossible to choose a universal external type of information storage that could satisfy the needs of each user, therefore, when choosing a device, it is necessary to take into account specific needs, for which the device will serve.

Classification

Depending on the characteristics of external storage devices, all data storage devices are divided into some classifications:
- Capacitive. They have a large amount of memory and can store huge amounts of data. Drives of this category allow you to record and store several tens of terabytes of information.
- High-speed. They have significantly less memory capacity compared to the previous category, however, they are able to write and read data very quickly. However, it should be noted right away that high-speed drives are not designed to store information for a long period of time.
- Simple. This category is the most popular among most modern users due to its low cost and ease of use. However, they do not possess any large amount of memory and high operating speed.
- Reliable. Storage devices of this category have a high resource of work and allow you to store electronic data for many decades.

Many consumers may have a question: "Which category of external storage devices should I give preference to?" There can be no unequivocal answer, as well as strict recommendations, since each type of storage is designed for a specific category of users and performs a specific function assigned to it. For example, the first category will do large companies that physically cannot place corporate information on servers. For the average user like you and me, the best option will become simple storage devices because they are inexpensive and very easy to use.

Nevertheless, it is worth noting that information cannot be stored on a computer's hard drive forever, since in the process of working at a computer, the HDD gradually deteriorates, as a result of which it may stop working one fine day. Therefore, it is recommended to create backups important files and electronic documents and store them somewhere other than a computer, for which external storage is ideal.

Optical storage

For many decades, optical drives, such as CDs, DVDs and Blu-ray discs, remained one of the most common external data storage devices, however, as technological progress developed, they gradually outlived their usefulness and were ousted from the market by more modern devices.

Optical drives were quite cheap and could write 700 megabytes or 4 gigabytes, depending on the type of disc. There are two types of discs: R and RW. The first type was designed for a one-time write, and the second allowed data to be overwritten, which made it more versatile. However, it should be noted right away that optical drives have low resistance to mechanical and physical stress, therefore, in the process of working with them, you must be extremely careful, otherwise you can very quickly render them unusable.
Today, optical discs are still used by some private users or small businesses who need to store documentation. The most popular are DVDs because they are inexpensive and can hold up to four gigabytes of information. However, to write data to this external storage device, your desktop or laptop computer must have a DVD-compatible burner.

As for the optical drives, then the high reliability was shown by the disks from Verbatim, and for recording data on them, you can purchase a drive from such manufacturers as LG, Samsung or Asus.

Nonvolatile data storage

Such devices include regular flash drives with USB interface or more modern solid state drives... However, when choosing such devices, it is necessary to take into account some of the nuances. Firstly, they have a fairly high cost with a small amount of physical memory, and secondly, their stability is at a rather low level. As practice shows, an ordinary computer USB flash drive can fail even if it is incorrectly removed from the port.

You shouldn't expect that the situation with flash drives will somehow change in the near future. The point is. That the cost of external drives in this category grows as the amount of memory itself increases, and that poor technical specifications significantly limit the applications in which flash memory can be used.

As for the recommendations of professionals, they do not recommend using USB flash drives and memory cards to store important information due to low reliability. But for short-term storage and transfer of data from one computer to another, they are just perfect. However, there is no need to build special illusions, since this memory has enough shortcomings. Despite the relatively low retail price, absolutely all flash drives do not tolerate contact with water, and the design of their case is very fragile, so you should be extremely careful when working with them.

The main characteristic of external drives with a USB interface, in addition to the amount of memory, is the speed of data read / write. It is not worth attaching special importance to the external design, body material, color and other similar trifles, since the quality of the controller itself plays the main role.

There are also no special problems with the choice of memory cards. Regardless of the type of memory card, the only parameter to which you should pay attention is the class of the drive, since the speed of the device depends on it. The higher the class, the faster the process of reading / writing data. The fastest class these days is the tenth, and as for the manufacturers, this does not really matter.
But when buying a USB flash drive, you will have to suffer a little, since modern manufacturers do not indicate the bandwidth in the technical documentation, so it is very difficult to determine the true speed of a particular device. The most common external USB drives are second-generation flash drives, which support transfer rates of about 10 MB per second, while third-generation USB drives are much faster.

The best option

If you are faced with the need to purchase an external storage device, then it is recommended to pay attention to solid-state hard drives or SSDs. These devices have not only excellent performance, but are also among the most reliable. This was achieved thanks to innovative technologies and modern cell structure.

Of course, if mechanical damage occurs as a result of excessive physical impact or negative influence of environmental factors, then the solid-state drive will become unusable, however, it can still be used as a large USB drive from which it will be possible to restore everything stored on it data. It is thanks to this that more and more users are switching to this type of hard drives.

In addition, when you calculate the equivalent cost, solid state drives provide the cheapest way to store electronic data sets. This type of storage is the optimal balance of cost and storage capacity. According to mathematical calculations that were made by some IT specialists, one gigabyte of space on a solid-state hard drive costs about fifteen rubles, which makes it the cheapest type of external storage device on the market compared to other types of storage and data transmission devices.

Thus, it is not too difficult to come to the conclusion that the smarter solution, in terms of economy, is to buy a drive that has more memory. If we talk about which manufacturer to give preference to, then there is no fundamental importance, since all modern companies on the market produce high-quality external storage devices of the solid-state type.

Future technologies

Today, the most advanced data recording and storage device with superior reliability and highest performance is the streamer, which records information onto a special high-density magnetic tape. It is this device that provides users with the largest amount of information storage. It should be noted that the volume of data stored by a streamer is measured not in megabytes, as is typical for all other types of external drives, but in terabytes. In addition, having a special encryption key, you can read information from the cassette from absolutely any device.

It is also worth noting that on the network you can find many special utilities with which you can encode and compress data, which allows you to write even more information. And, despite the fact that this method of recording, storing and transferring data was invented in the distant future, it remains relevant today due to the lack of more modern devices that could surpass streamers in their technologies.

However, there is one caveat. The thing is that streamers are not available for sale, so an ordinary user will not be able to just go to a computer store and buy this device for himself. And there are many problems with the synchronization of the streamer and the computer. However, some domestic manufacturers have already developed and released special adapters, with the help of which there will be absolutely no problems with connecting a streamer.

Guests from the past

There is another type of external storage device, which is called a floppy disk, however, an older generation worked with it or saw it in the eyes. Nowadays, it is impossible to see this external drive on the store shelves, since it has been out of production for more than ten years. This type of storage is one of the most unreliable, since it is possible to disable it and lose all the information stored on it simply by negligence. The thing is that the principle of operation of a floppy disk is based on an electromagnetic field, therefore, leaving it even for a short time near the magnet, the flexible medium is demagnetized and all data is lost forever. To protect against data loss, special cases were used to prevent exposure of the floppy disk to electromagnetic fields.

Representatives of the budget category

Ordinary hard drives, which are used in stationary computers, placed in a protective case and equipped with a mini-USB connector designed for synchronization with a computer, can also act as external data storage devices. He is responsible not only for data transmission, but also for powering the device. In terms of stability and reliability, external HDDs are practically on par with other types of external drives, and some are even superior. User distrust of these devices is caused by frequent system Windows crashes that lead to data loss, however, this is purely software in nature and has nothing to do with the hardware. Moreover, the lost information can be easily recovered using special software.

As for the advantages, external hard disks have a high resource of work, and the recorded data can be stored on them for several decades. In addition, hard drives are excellent value for money, after trimers, in terms of the cheapness of one unit of memory.

The main criteria for choosing an external HDD, in addition to the volume, which is a standard parameter, is the operating speed, which is directly dependent on the rotation speed of the magnetic head reading information from magnetic drives.

Given these characteristics, differential backups deserve careful consideration. Only medium or set of media is required to recover files. If the files change infrequently, the backups will be almost the same. Provides faster backups.

Provides backups faster than regular backups. If there are many changes to the data, backups may take longer than incremental backups. The tape was the first widely used removable storage medium. It has a low cost and a fairly good capacity. However, the tape has some disadvantages. It is subject to wear and tear, and access to data on the tape is inherently sequential. These factors mean that you need to track tape usage, and that finding a specific tape file can be a time-consuming task.

The purpose

Any electronic device that can be found on store shelves is designed to perform specific tasks. External data storage devices are no exception and allow you to store large amounts of information in electronic form, which can be stored undamaged for a long period of time. However, for this, external drives must have a sufficient amount of memory that would allow recording large data packets, and also have high reliability so that information does not disappear from the device's memory.
Among the main technical characteristics of external data storage devices that you need to pay attention to when buying a device are:
- read / write speed, on which the speed of the device depends;
- the quality of the components from which the gadget was made;
- availability of data encryption function, significantly increasing the level of protection of confidential information stored on the drive;
- compatibility, on which the ability to synchronize external drives with other devices and operating systems depends.

On the other hand, tape is one of the cheaper media and has a long reputation for reliability. This means that creating a reasonably sized tape library does not take up a significant chunk of your budget, and you can count on it for current and future use.

The problem is that the cost of the equipment is relatively high and the tapes are not very reliable, which ultimately obliges the operator to always make at least two copies in order to have a higher level of security. For those with a small business or home user, they are definitely not worth it.

Classification

There are two types of hardware on a computer: internal and external. The efficient exchange of information between hardware components, as well as the ability to store some data, is what leaves a computer slow or fast. It contains information that is created or controlled by the user and sends it to the processor. With the current promotion electronic components more and more computers are becoming powerful and also more and more expensive. New parts are released every day and often do not hold up to all the features offered by the hardware.

What can damage the external hard drive?

There are many reasons that can damage your storage device. Below is a list of causes that can damage your external hard drive. The storage device has bad sectors. File system error.

How to recover corrupted files from external hard drive?

But if the error has already occurred, how to fix it? If your external hard drive can be detected by your computer, but the saved files are corrupted, you can try the following steps to recover the corrupted external hard drive files.

It will help you recover your damaged external hard drive and files on it. If you are unable to access data stored on your damaged external hard drive, don't worry. Read on and find solutions in the passages below.

How to recover data or files from an external hard drive?

When your storage device such as an external hard drive is suddenly damaged, the most urgent is to recover data or files from the external hard drive. Here are two ways to fix this problem. If the disc is readable, you can directly use your data on an external hard drive.

Thus, it is not too difficult to come to the conclusion that the smarter solution, in terms of economy, is to buy a drive that has more memory. If we talk about which manufacturer to give preference to, then there is no fundamental significance, since all modern companies on the market produce high-quality external storage devices of the solid-state type.

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Ordinary hard drives, which are used in stationary computers, placed in a protective case and equipped with a mini-USB connector designed for synchronization with a computer, can also act as external data storage devices. He is responsible not only for data transmission, but also for powering the device. In terms of stability and reliability, external HDDs are practically on par with other types of external drives, and some are even superior. User distrust of these devices is caused by frequent Windows system failures, which lead to data loss, however, this is purely software in nature and has nothing to do with the hardware. Moreover, the lost information can be easily recovered using special software.

The attractiveness of the USB interface is in its simplicity - just plug in a USB flash drive or other storage device and you can work, no driver installation or other additional steps are required. The development of the interface and the emergence of first USB 2.0, and then USB 3.0 dramatically increased the speed of data exchange over this channel. The performance now differs little from the internal one, and their size cannot but rejoice. The external memory drive fits easily in the palm of your hand and can store hundreds of gigabytes of information.

Data storage. Internal and external storage

general information

ADATA HD 710

Hard drive. External hard drive HGST Touro Mobile MX3

Seagate Expansion Portable

Seagate Expansion

Silicon Power Armor A80

TOSHIBA Stor.E Basics

Transcend StoreJet 25H3

Western Digital My Passport Ultra

Flash drives

External HDs

Bare interface

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Bridges of all countries, unite!

Bridges, you say ... well, well

What can damage the external hard drive?

How to recover corrupted files from external hard drive?

How to recover data or files from an external hard drive?

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