Information storage is a whole science. Information storage

Storage and accumulation of information caused by its repeated use, the use of constant information, the need to complete the primary data before processing them.

Information storage is carried out on computer media in the form of information arrays, where the data is located according to the grouping criterion established during the design process.

Data search- ϶ᴛᴏ selection of the required data from the stored information, including the search for information to be corrected or replacing the request for the required information.

The basic principle of storing information can be formulated as follows: the stored information always has the form of a "trace", an imprint on some medium.

The type of media does not matter. This can be stone, wood, paper, magnetic tape, or film. A trace in the form of a certain letter-sign on a stone, wood, paper can be applied directly by a human hand armed with a chisel, brush or pencil. It is worth noting that it is visible to the naked eye and can be easily read.

The use of photographic film, magnetic tape and laser disk as information carriers requires special devices - information converters. So, for recording information on a photographic film, a camera is required, and for reading information, a projector is required. Magnetic recording and reading of information is carried out using a more complex device - a tape recorder.

A characteristic feature of all these types of media will be the need for special technical devices for both recording and reading information. This means the possibility of mechanizing and automating the processes of recording and reading information, making them independent of the presence of a person.

A variety of storage devices are used to store large amounts of information. Very large amounts of information are stored on external storage devices (OVC) These include storage devices on:

• disks (ZUD);
• magnetic drum (MB);
• magnetic tapes (ML);
• perforated tapes (PL);
• magnetic cards (MK), etc.

The reduced VCUs belong to the class of memory with the movement of the information carrier. The advantage of such storage devices, along with a large capacity, will be the low cost of storing a unit of information, and the disadvantage is the presence of mechanical movement units, which impose restrictions on the speed of work. From the standpoint of organizing the storage of information, VCUs are subdivided into memory with a non-removable medium, or memory with a removable medium (MB, MK), which make it possible to create libraries and archives with an almost unlimited amount of data. The movement of the medium during reading can be continuous (MB, ZUD) or start-stop (ML, PL), in which case it occurs only during the access to the VCU. The selection of blocks of information from the memory at m is made according to the principle of sequential or random access. In the latter case, a block of information with an arbitrary address is selected for a constant period of time. By the organization of communication, a distinction is made between OVCs operating under the control of a machine (connected to it automatically without operator intervention) and uncontrolled by a machine (requiring the participation of an operator in the installation of blocks with stored information). optical reproduction, etc.

Disk storage device- ϶ᴛᴏ memory, in which a magnetic disk is used as a storage device. It is worth noting that it consists of a drive (pack of discs), a sampling unit (a set of magnetic heads with pneumatic or hydraulic drive and an electronic system for converting the address code into the next movement of the heads), a recording-reading unit (a set of playback and recording amplifiers) and a block local government. The speed of the memory is determined by the speed of rotation of the disks and the adopted sampling system. The average access time to the RAM is 15 - 150 ms, and the capacity is 10 7 - 8-10 10 bits. It is used as an external storage device for storing large amounts of information and large program libraries.

A memory device on a magnetic drum - ϶ᴛᴏ memory, in which a magnetic drum (MB) is used as an information storage device It should be said that to implement access to the memory on the MB, a track of synchronizing markers applied to the MB is used during the manufacturing process. The marker signals read by the magnetic head, after amplification, are fed to the address counter, which is set to zero position before the arrival of the first synchronizing marker. The contents of the counter are compared with the contents of the address register. At the moment of coincidence of the counter indicator with the address code specified by the command, an access signal is issued, according to which the number is written or read. The access time to memory per MB is determined by the MB turnover time and is tens of milliseconds. Up to 10 7 - 10 8 bits of information are located on the surface of the MB. MB memory is used mainly as an external storage device.

Today, the improvement of the computer as a universal means of information processing has led to the creation of a number of devices specially designed for storing information in electronic form.

It should be remembered that modern materials such as film and magnetic tape can satisfy most requirements, but they are not without drawbacks. It is well known that over time, photographs darken, listening to gramophone records is accompanied by crackling, and magnetic recordings, after repeated playback, begin to "make noise". Today, the most common way of storing information is magnetic recording... But it can also be damaged by temperature or magnet.

For storing information in automated systems controlled by a computer, magnetic tapes can be used less and less, their place was taken by magnetic disks. The principle of recording information on a magnetic disk is the same as on a magnetic tape. The only difference is that the recording on a magnetic tape is performed sequentially, one after the other, and is also read, and on a magnetic disk the recording is sequential, and the reading can be carried out in any order.

Magnetic disc is a thin, flexible plastic disk coated on both sides with magnetic powder similar to that used in magnetic tapes. This allows you to record information on both of its surfaces, thereby achieving a twofold increase in its information capacity. So that when working with a disk it is not necessary to turn it over, recording and reading is carried out by two magnetic heads (each on the ϲʙᴏ side of the disk) This type of media is called “ flexible magnetic disk ", and the device for reading and writing information is not him - drive.

But along with convenience (lightness, compactness, durability), it also has disadvantages: high temperature destroys the recorded information, thin material requires careful handling, humidity makes it difficult to read. Back in the mid-60s, the idea of ​​creating a disk from a hard material and placed in a closed volume appeared, from which air was pumped out (at ϶ᴛᴏm, neither heat nor humidity is afraid of it) Such a disk was named "HDD" (hard disk) or Winchester.

To increase the information capacity, a hard drive is made of several disks located on the same axis, and the size of the magnetic heads is reduced, achieving narrower magnetic tracks recorded on the disk. This allows tens and hundreds of times to increase the amount of information recorded on such a disk, with increased reliability of its storage.

At the same time, an increase in the information capacity of a hard drive in comparison with a flexible magnetic disk deprives it of its mobility. Material published on http: // site
A hard disk is much heavier than a floppy disk, more difficult to connect and inconvenient to transfer from one computer to another. Therefore, today a hard drive is used to store large amounts of information, and a flexible magnetic disk is used to transfer small portions of information from one computer to another.

Over time, the amount of information with which a person works and which he needs to transfer to another person, increased until it exceeded the information capacity of a floppy disk as a mobile (portable) means of storing information. This led first to the "revival" of magnetic tape cassettes as mobile storage media (their large capacity, despite the inconvenience of searching and reading information, gives them an advantage over floppy disks), and then to the creation of a new type of media - laser disk.

Laser disc- a three-layer disc made of glass or durable plastic. In it, between two thin protective layers of plastic (glass), a thin layer of metal foil made of silver or even gold is placed. Information is recorded on such a disk by a laser beam that runs along a spiral path from the edge of the disk to its center and burns out microscopic "holes" in the metal foil. The information is encoded by the number of "holes" and their location on the spiral track. The laser beam is very thin, and the width of the path is ten times thinner than a human hair. This makes it possible to obtain information recording density unattainable for magnetic disks. Information reading is carried out by a weak laser beam. The burned-out and preserved areas of the foil reflect the beam in different ways. The reflected beam is captured by a photocell and decoded. Laser discs are otherwise called optical, since the writing and reading of information is carried out with the help of light.

But you can record information on a laser disk only once, because the metal foil is already "damaged". This means that, unlike a magnetic disk, a laser disk does not allow rewriting information and is only readable. Therefore, it is not able to replace magnetic disks and tapes. At the same time, there is no more convenient medium for storing unchanged information.

In recent years, materials have been found that combine the advantages of magnetic and optical media and make it possible to rewrite information stored on a disk.
It is worth noting that the main advantages magneto-optical disks there will be large information capacity, compactness, mobility, the ability to rewrite stored information.

Types of storage media

Information carrier- a physical medium that directly stores information. The main carrier of information for a person is his own biological memory (human brain). A person's own memory can be called working memory. Here the word "operational" is synonymous with the word "fast". Learned knowledge is reproduced by a person instantly. We can also call our own memory internal memory, since its carrier - the brain - is inside us.

Information carrier- a strictly defined part of a specific information system, serving for intermediate storage or transmission of information.

The basis of modern information technology is a computer. When it comes to computers, we can talk about storage media as external storage devices (external memory). These storage media can be classified according to various criteria, for example, by the type of performance, the material from which the media is made, etc. One of the options for the classification of information carriers is shown in Fig. 1.1.

List of information carriers in fig. 1.1 is not exhaustive. We will consider some storage media in more detail in the following sections.

Tape media

Magnetic tape- magnetic recording medium, which is a thin flexible tape, consisting of a base and a magnetic working layer. The operating properties of a magnetic tape are characterized by its sensitivity during recording and signal distortion during recording and playback. The most widely used is a multilayer magnetic tape with a working layer of needle-like particles of magnetically hard powders of gamma iron oxide (y-Fe2O3), chromium dioxide (CrO2), and gamma iron oxide modified with cobalt, usually oriented in the direction of magnetization during recording.

Disk storage media

Disk storage media belong to machine media with direct access. Direct access means that the PC can "access" the track on which the section with the required information begins or where new information needs to be recorded.

Disk drives are the most diverse:

• Floppy disk drives (floppy disks), they are also floppy disks, they are also floppy disks
• Hard disk drives (HDD), they are also hard drives (popularly just "screws")
• Optical CD Drives:
• CD-ROM (Compact Disk ROM)
• DVD-ROM

Floppy disk drives

Some time ago, floppy disks were the most popular means of transferring information from computer to computer, since the Internet was very rare in those days, computer networks too, and CD-ROM drives were very expensive. Floppy disks are still used now, but they are already quite rare. Mainly for storing various keys (for example, when working with the client-bank system) and for transmitting various reporting information to state supervisory services.

Diskette- portable magnetic storage medium used for multiple recording and storage of data of a relatively small volume. This type of media was especially common in the 1970s and early 2000s. Instead of the term "floppy disk", the abbreviation HMD is sometimes used - "floppy disk" (accordingly, the device for working with floppy disks is called "floppy disk drive" cookie "). Typically, a floppy disk is a flexible plastic plate covered with a ferromagnetic layer, hence the English name "floppy disk". This plate is housed in a plastic case that protects the magnetic layer from physical damage. The casing is flexible or durable. Floppy disks are written and read using a special device - a floppy drive. A floppy disk usually has a write protection feature, through which you can provide read-only access to data. The appearance of a 3.5 ”floppy disk is shown in Fig. 1.2.

Hard disk drives

As drives on hard magnetic disks, hard drives are widely used in PCs.

Term Winchester originated from the slang name of the first model of a 16KW hard disk (IBM, 1973), which had 30 tracks of 30 sectors, which coincidentally coincided with the caliber 30/30 of the famous Winchester hunting rifle.

Optical drives

Compact disc("CD", "Shape CD", "CD-ROM", "CD ROM") - an optical storage medium in the form of a disc with a hole in the center, information from which is read using a laser. The CD was originally created for digital storage of audio (called Audio-CD), but is now widely used as a general purpose storage device (called CD-ROM). Audio CDs differ in format from data CDs, and CD players can usually only play them (you can, of course, read both kinds of discs on a computer). There are discs containing both audio information and data - you can listen to them on a CD-player and read them on a computer.

Optical discs usually have a polycarbonate or glass heat-treated base. The working layer of optical discs is made in the form of the thinnest films of low-melting metals (tellurium) or alloys (tellurium-selenium, tellurium-carbon, tellurium-selenium-lead, etc.), organic dyes. The information surface of optical discs is covered with a millimeter layer of durable transparent plastic (polycarbonate). In the process of recording and playback on optical discs, the role of a signal converter is played by a laser beam focused on the working layer of the disc into a spot with a diameter of about 1 μm. When the disk rotates, the laser beam follows the track of the disk, the width of which is also close to 1 µm. The ability to focus the beam into a small spot makes it possible to form marks on the disk with an area of ​​1-3 microns. Lasers (argon, helium-cadmium, etc.) are used as a light source. As a result, the recording density turns out to be several orders of magnitude higher than the limit provided by the magnetic recording method. The information capacity of an optical disk reaches 1 GB (with a disk diameter of 130 mm) and 2-4 GB (with a diameter of 300 mm).

They are also widely used as information carriers. magneto-optical compact discs type RW (Re Writeble). Information is recorded on them by a magnetic head with the simultaneous use of a laser beam. The laser beam heats up a point on the disc, and an electromagnet changes the magnetic orientation of that point. The reading is carried out by a laser beam of lower power.

In the second half of the 1990s, new, very promising carriers of documented information appeared - digital universal video discs DVD (Digital Versatile Disk) such as DVD-ROM, DVD-RAM, DVD-R with a large capacity (up to 17 GB).

In terms of application technology, optical, magneto-optical and digital CDs are divided into 3 main classes:

1. Discs with permanent (non-erasable) information (CD-ROM). These are plastic CDs with a diameter of 4.72 "and a thickness of 0.05". They are made using an original glass disc on which a photo-recording layer is applied. In this layer, the laser recording system forms a system of pits (marks in the form of microscopic depressions), which is then transferred to the replicated discs-copies. Information reading is also carried out by a laser beam in the optical drive of a personal computer. CD-ROMs usually have a capacity of 650 MB and are used to record digital sound programs, computer software, and the like;
2. Discs that allow one-time recording and multiple reproduction of signals without the possibility of erasing them (CD-R; CD-WORM - Write-Once, Read-Many - recorded once, read many times). They are used in electronic archives and data banks, in external computer storage devices. They represent a base made of transparent material, on which a working layer is applied;
3. Reversible optical discs capable of rewriting, playing back and erasing signals (CD-RW; CD-E). These are the most versatile drives that can replace magnetic media in virtually all applications. They are similar to write-once discs, but contain a working layer in which the physical recording processes are reversible. The manufacturing technology of such discs is more complicated, so they cost more than write-once discs.

Electronic storage media

Generally speaking, all previously considered carriers are also indirectly related to electronics. However, there is a kind of media where information is stored not on magnetic / optical disks, but in memory chips. These microcircuits are made using FLASH technology, therefore such devices are sometimes called FLASH disks (popularly just a "flash drive"). The microcircuit, as you might guess, is not a disk. However, operating systems, storage media with FLASH memory are defined as a disk (for the convenience of the user), so the name “disk” has a right to exist.

Flash memory (English Flash-Memory) is a kind of solid-state semiconductor non-volatile rewritable memory. Flash memory can be read as many times as you like, but you can write to such memory only a limited number of times (usually about 10 thousand times). Despite the fact that there is such a limitation, 10 thousand rewriting cycles is much more than a floppy disk or CD-RW can withstand. Erasing occurs in sections, so you cannot change one bit or byte without rewriting the entire section (this limitation applies to the most popular type of flash memory today - NAND). The advantage of flash memory over conventional memory is its non-volatility - when the power is turned off, the contents of the memory are saved. The advantage of flash memory over hard drives, CD-ROMs, DVDs is the absence of moving parts. Therefore, flash memory is more compact, cheaper (considering the cost of read / write devices), and provides faster access.

Data storage

Data storage is a way of spreading information in space and time. The way of storing information depends on its medium (a book is a library, a picture is a museum, a photograph is an album). This process is as ancient as the life of human civilization. Already in ancient times, a person was faced with the need to store information: notches in trees, so as not to get lost during a hunt; counting objects with the help of pebbles, knots; depictions of animals and hunting episodes on the walls of the caves.

The computer is designed for compact storage of information with the ability to quickly access it.

Information system- is a repository of information, equipped with procedures for entering, searching and placing and issuing information. The presence of such procedures is the main feature of information systems, distinguishing them from simple accumulations of information materials.

From information to data

A person has different approaches to storing information. It all depends on how much of it and how long it needs to be stored. If there is little information, it can be memorized in the mind. It is not difficult to remember your friend's name and surname. And if you need to remember his phone number and home address, we use a notebook. When information is stored (stored) it is called data.

The data in the computer has different purposes. Some of them are needed only for a short period, others need to be stored for a long time. Generally speaking, there are quite a few "tricky" devices in the computer that are designed to store information. For example, processor registers, register cache memory, etc. But most of the "mere mortals" have not even heard such "terrible" words. Therefore, we will restrict ourselves to consideration of random access memory (RAM) and read-only memory, which include the storage media we have already considered.

Computer RAM

As already mentioned, the computer also has several means for storing information. The fastest way to memorize data is to write it to electronic chips. This memory is called random access memory. Random access memory consists of cells. Each cell can store one byte of data.

Each cell has its own address. We can assume that this is, as it were, a cell number, therefore such cells are also called address cells. When a computer sends data for storage to RAM, it remembers the addresses where the data is placed. Referring to the address cell, the computer finds in it a byte of data.

Regeneration of RAM

The address cell of the random access memory stores one byte, and since a byte consists of eight bits, there are eight bit cells in it. Each bit cell of the random access memory chip stores an electrical charge.

The charges cannot be stored in the cells for a long time - they "drain". In just a few tenths of a second, the charge in the cell is reduced so much that the data is lost.

Disk memory

For permanent storage of data, information carriers are used (see the section "Types of information carriers"). Compact disks and floppy disks are relatively slow, so most of the information that needs constant access is stored on the hard disk. All information on the disk is stored as files. There is a file system to control access to information. There are several types of file systems.

Data structure on disk

So that the data can not only be written to the hard disk, and then also read, you need to know exactly what was written and where. All data must have an address. Each book in the library has its own room, rack, shelf and inventory number - this is, as it were, its address. The book can be found at this address. All data that is written to the hard disk must also have an address, otherwise they cannot be found.

File systems

It is worth noting that the structure of data on a disk depends on the type of file system. All file systems are made up of structures needed to store and manage data. These structures typically include the operating system boot record, directories, and files. The file system also has three main functions:

1. Tracking used and free space
2. Support for directory and file names
3. Track the physical location of each file on disk.

• FAT (File Allocation Table)
• FAT32 (File Allocation Table 32)
• NTFS (New Technology File System)
• HPFS (High Performance File System)
• NetWare File System
• Linux Ext2 and Linux Swap

FAT

The FAT file system is used by DOS, Windows 3.x, and Windows 95. The FAT file system is also available in Windows 98 / Me / NT / 2000 and OS / 2.

The FAT file system is implemented using a File Allocation Table (FAT) and clusters. FAT is the heart of the file system. For security, the FAT has a duplicate to protect its data from accidental erasure or malfunction. A cluster is the smallest unit of the FAT system for storing data. One cluster consists of a fixed number of disk sectors. The FAT records which clusters are in use, which are free, and where the files are located within the clusters.

FAT-32

FAT32 is a file system that can be used by Windows 95 OEM Service Release 2 (version 4.00.950B), Windows 98, Windows Me and Windows 2000. However, DOS, Windows 3.x, Windows NT 3.51 / 4.0, earlier versions of Windows 95 and OS / 2 do not recognize FAT32 and cannot download or use files on a disk or FAT32 partition.

FAT32 is an evolution of the FAT file system. It is based on a 32-bit file allocation table, which is faster than the 16-bit tables used by the FAT system. As a result, FAT32 supports much larger disks or partitions (up to 2 TB).

NTFS

NTFS (New Technology File System) is only available on Windows NT / 2000. NTFS is not recommended for use on drives smaller than 400 MB because it requires a lot of space for system structures.

The central structure of the NTFS file system is the MFT (Master File Table). NTFS maintains multiple copies of the critical portion of the table to protect against problems and data loss.

HPFS

HPFS (High Performance File System) is a privileged file system for OS / 2 that is also supported by older versions of Windows NT.

Unlike FAT file systems, HPFS sorts its directories based on file names. HPFS also uses a more efficient structure for organizing the directory. As a result, file access is often faster and space is used more efficiently than with the FAT file system.

HPFS distributes file data into sectors, not clusters. To save a track that has sectors or is not used, HPFS organizes the disk or partition into 8 MB groups. This grouping improves performance because the read / write heads do not have to go back to track 0 every time the OS needs to access information about the available space or the location of a required file.

NetWare File System

The Novell NetWare operating system uses the NetWare file system, which was designed specifically for use by NetWare services.

Linux Ext2 and Linux Swap

The Linux Ext2 and Linux file systems were developed for Linux OS (Free UNIX version). The Linux Ext2 file system supports a disk or partition with a maximum size of 4 TB.

Directories and file path

Let us consider, for example, the structure of the disk space of the FAT system, as the simplest one.

A disk space information structure is a user-oriented external representation of disk space, defined by elements such as volume (logical drive), directory (folder, directory), and file. These elements are used when the user communicates with the operating system. Communication is carried out using commands that perform operations to access files and directories.

Sources of information

1. Computer Science: Textbook. - 3rd revision ed. / Ed. N.V. Makarova. - M .: Finance and statistics, 2002. - 768 p .: ill.
2. Wolf V.K. Study of the functional structure of the memory of a personal computer. Laboratory workshop. Tutorial. Publishing House of Kurgan State University, 2004 - 72 p.

When there was a lot of information surrounding a person, and he was unable to remember it, writing arose. Over time, it has improved and has become an integral part of a person's daily life. However, a large number of paper media makes it difficult to quickly find the information you need, and with the advent of digital information and means for its transformation and storage, it became possible to look at this problem differently. Digital information has a number of advantages related to immunity to transmission interference and longer

Information storage is one of the main ones with which the concept of information storage device, or memory device, is inextricably linked. Different devices can use different ways of storing information. The collection of such devices is called memory. More often the concept of "information storage" is associated with computer technology.

Computer memory can be internal and external. Internal memory includes devices that ensure the operability of the computing system itself (computer). For example, operational Most of the storage devices known to the average user, such as a hard drive, USB flash drive, CD, belong to

Until recently, this was the only thing that the computer industry had to offer us. Now anyone has the opportunity to store their personal information directly on the Internet, and without even spending money on it.

On the one hand, it is very convenient, since you can access and view the necessary information from any device that has it. Thus, cases are excluded when a flash drive with information is forgotten at home, just on the day when it was really needed at work.

Storage of information is accompanied by one unpleasant moment associated with its damage, loss, or any experienced user knows several tricks on how to protect their information from loss. For example, you should not store valuable information on the hard drive, as there is a high probability of "picking up" a virus that will destroy everything. You can also duplicate important information on several media at once.

Such information is usually stored on removable storage devices for which certain storage conditions are created. But there is another way to ensure reliable storage of information.

This is the use of "cloud" Internet services, in which case user information is stored on distributed servers on the Internet, and access to it is carried out by means of a username and password. This technology has roughly equal shares of allies and opponents. Some do not trust the global network at all with their personal files, while others, on the contrary, see the future in this.

In the modern world, especially in large cities where access to the global network is everywhere, such information storage seems preferable. There is no need to buy, maintain and tremble over the safety of photos or video archives.

But what will happen if the Internet connection is suddenly cut off and the user cannot access his information at the right time?

How to ensure the safety of information? Don't rush to answer this seemingly simple question. First, take a close look at the advantages and disadvantages of the available storage media. Manufacturers will help you with advantages, and we will raise the pitfalls from the abyss of information together in this article.

How to ensure the safety of information? What materials to use in this case? What should be considered when choosing storage media? Don't rush to answer these seemingly simple questions. To get started, you should carefully examine the advantages and disadvantages of the available storage media. Manufacturers will help you with advantages, and we will raise the pitfalls from the abyss of information together with you in this article.

Sometimes a random napkin or old business card is enough to preserve vital information. But for recording a financial report or video from a recent corporate party, such storage media are unlikely to work. In addition, there are vast amounts of information of legal, commercial, historical or scientific value. It must be stored for years or even centuries, and therefore the choice of storage medium is of paramount importance. What to choose in a dynamic world of technological innovations and old proven media? We bring to your attention an overview of the main storage media from their most unsightly side.

Paper

Paper is the oldest means of storing information. As you know, a spontaneous change in the properties of paper as a result of aging is associated with a change in the chemical structure and, in particular, its main component - cellulose. The development of technology has had a positive effect on the quality of materials used in production. New processing procedures have significantly improved the physical, chemical and electrostatic properties of paper. Scientific advances have also led to more advanced ways of applying information: carbon black and nib inks, slate pencils, fountain pens, printing ink, typewriter ribbons, and printer inks.

The way information is applied, as well as the quality of the material itself, ultimately determine the long-term storage of data on paper. Our ancestors wrote letters with a stylus or ink based on carbon, which does not change its properties for centuries and is a chemically resistant substance. The text was usually applied using physical damage to the surface - the punching method. The same technology was used for typewriters and dot-matrix printers, in which inorganic dyes were sprayed by a contact method: first, the paper was pressed through, and then the dye penetrated into the material to a predetermined depth.

This old method of applying information by means of mechanical punching is not comparable to what is used today in conventional inkjet and laser printers. An inkjet printer sprays liquid ink from a specific distance without physically altering the surface. Manufacturers do not report the depth of ink penetration, however, as well as what they are made of. The situation is even worse with laser printers. According to the technology, toner powder is applied to paper, then the sheet passes through rollers heated to a high temperature, and the powder granules are sintered. In this case, the toner is often not absorbed into the paper at all. There are cases when, after a few years, the paint simply fell off the sheet in whole pieces, like fragments of an old mosaic.

camera roll

Photographic film is doing much better than paper.

Firstly, the production technologies of at least black-and-white film are time-tested. They practically do not change, so it is safe to say that the materials will be preserved for a long time, even if you buy the most ordinary film from the nearest photo store. At the same time, the chances of a long life for professional films are certainly higher, since they differ from amateur films with special additives that slow down the aging process. However, the requirements for the storage conditions of professional films are somewhat stricter.

Secondly, unlike paper, photographic film has a shelf life, during which manufacturers guarantee the preservation of its properties. After this time, a chemical process begins, causing aging of the photographic film, which can be contained if the temperature, humidity and light storage conditions are observed.

A significant drawback in working with photographic film is that the cost of film and equipment (camera or camera, reagents for developing and fixing a picture, projectors for viewing finished materials) is relatively high.

Magnetic tape

You probably remember your old cassette recorder, which was later replaced by video players and VCRs. The media in them were removable cassettes. With the development of information technology, magnetic tape began to be used for storing information in digital form.

Special devices (streamers) digitally record information on tape, which is stored in approximately the same way as on a computer: in the form of files. Previously, streamers were widely used to store data backups. In everyday life, such devices did not take root. First of all, this is due to the complexity of access to the information recorded on the tape. First, you need to rewind it to the place where the necessary information is written, and then wait until the data is read into the computer's memory. Not everyone will have the patience for such technological troubles. At one time, expansion cards for a computer were produced, with the help of which it was possible to store data on audio cassettes, and later on video cassettes, using in conjunction with a card that is inserted into a computer, an audio or video recorder.

The long-term storage of information on a magnetic tape largely depends on the quality of the tape itself. For example, there are low-quality tapes, the magnetic layer from which simply crumbles over time, and if you see noise in the video, then reading digital data from such a tape will be problematic. A special tape for a streamer is designed for longer storage of information and more active use. This is due to the fact that when recording on a tape, a special coding of information is used, which allows it to be reliably restored when reading it, even if some bits of information are decoded incorrectly (the user will not notice anything). In addition, several copies of data can be simultaneously created during recording (several tracks can be written in parallel on the width of the tape), which also has a positive effect on the storage time.

A problem that potentially awaits every hobbyist of magnetic tape is the rapid obsolescence of equipment. It is not a fact that in a few years, if the current device breaks down, you will be able to find a replacement for it, even just to read the data and transfer it to a new medium. Another unpleasant moment in working with magnetic tape: cassettes must be rewound regularly. Otherwise, the contacting layers of the film magnetize each other, which means that the magnetic tape will not be able to reliably store information for a long time. In industrial equipment, robotic systems are used that automatically change cassettes as they fill up and periodically rewind tapes.

Store tapes with extreme caution, as the magnetic fields that surround us and are completely invisible can damage the information on the tape. Thus, the use of ferromagnetic metal racks is not allowed. When placing the film on steel shelves, it is necessary to demagnetize and close the contours of the shelf: connecting the metal parts of the shelf with an electric wire and their effective grounding. It will not be superfluous to recall that magnetic tape, like any medium, also requires compliance with a certain temperature and humidity regime.

Floppy disks

CD / DVD

Low cost and general availability are the main advantages of CDs and DVDs. But, unfortunately, information on them is often completely (or partially) lost after two or three years. This is due to the destruction of the coloring layer caused by exposure to sunlight and ionizing radiation.

Sometimes in the production of large quantities, stamping is used, similar to the production of vinyl records. Unlike regular CDs and DVDs, these discs can last for years.

Manufacturers claim that given the correct storage conditions, some types of discs (CD-R, DVD-R) can be used for 100 to 200 years. However, in practice, these optimistic statements are not confirmed.

Hard disk drive (HDD)

Today, perhaps the most common device for storing information. Hard drives can be internal (installed inside the case) and external (connected to the device using a USB cable). In the latter case, the hard drive is sized to be carried in a jacket pocket and connected to almost any computer via a USB connector.

Every year the cost per unit of stored information decreases. The information is stored on plates inside a sealed container covered with a magnetic material. The recording technology is like magnetic tape, and the device itself is like a floppy disk. The main difference is in the materials used. In addition, the hard disk contains, firstly, electronics that can fail, for example, from a power surge in the network, and secondly, high-precision mechanics. Due to the fact that the reading heads do not touch the surface of the disk during operation, the surface does not wear out and can serve to store information for many years.

In case of careless handling (falling, shaking during operation), hard drives are susceptible to failure. So, one sharp shaking of a fully functional disk may be quite enough to lose all the information recorded on it without the possibility of recovery. With careful handling, the discs will serve well for more than ten years with active everyday use. However, recently the quality of equipment leaves much to be desired, since in the pursuit of a low price, manufacturers save on equipment and materials.

Flash memory, flash drives

Flash drives are storage media that use electrically erasable, non-volatile memory for storage. If magnetic tape, floppy disks and hard disks were invented and widely used at the dawn of computer technology, then flash memory has become popular relatively recently. This is due to a breakthrough in chip technology.

There are both expensive large-capacity solid-state drives and budget devices known as flash drives and memory cards. Today they are, perhaps, the most affordable and convenient means for everyday use. The memory card is a completely electronic device and can be connected to the device via a card reader. In contrast, flash drives do not require additional mechanisms to connect to a computer.

The reliability of information storage declared by manufacturers is up to ten years. Unlike hard drives, flash drives are not afraid of shocks and drops from low heights. They are lightweight, roomy and have high storage capacity to store multiple movies or tens of thousands of documents on a single device.

With everyday use, flash drives are quite often damaged, for example, from static electricity, which damages delicate electronics. The reason may also lie in poor quality workmanship and mistakes made by engineers when designing cheap devices, especially flash drives. The latter can fail due to a breakdown of the microcontroller. In this case, the information can theoretically be restored directly from the memory chip using special equipment. If the microcircuit itself is damaged, then the data cannot be restored.

Technology does not stand still. And today scientists are already creating such information carriers that, for ordinary people, seem to be part of science fiction plots. However, when choosing a storage medium, one should be guided not only by fashionable technological trends, but also by common sense. If a few mobile gigabytes of free space (the size of a standard flash drive) is enough for you to store information, then there is no point in buying expensive gigantic hard drives just to impress your friends.

In addition, it is necessary to take into account the costs of both the purchase of the media itself and the costs associated with recording information and maintaining equipment (for example, as in the case of photographic film). In order to ensure reliable data safety, the optimal solution would be to choose not one, but several storage media that can help each other in case of annoying damage to one of the media.

Modern methods of storing information can be divided into two groups - methods of storage on physical media and methods of storage based on cloud technologies.

Existing physical storage media include optical disks, solid-state media, and magnetic hard disks. Optical disks allow you to store a limited amount of information, have a low write speed, and are sensitive to mechanical damage and temperature. The most common storage media are solid-state storage media (flash cards, memory cards, solid-state hard drives). They are characterized by high write speed, small size and resistance to mechanical damage, the amount of sensitive information is much larger than that of optical disks, but still inferior to the volumes stored on hard magnetic disks. Magnetic hard disks are distinguished by high speed of information recording, high reliability of data storage and large amounts of memory, however, they are very sensitive to mechanical stress.

Recently, cloud storage technologies are gaining popularity. Information is stored on numerous servers distributed in the network, while users do not see the structure of the servers, they work in the cloud - one large virtual server.

One of the popular cloud data storage is Google Drive (https://drive.google.com), which allows you to store 30 types of files, provides tools for working with documents online. The amount of free space is 15GB, you can additionally purchase from 100GB ($ 1.99 per month) to 30TB ($ 299.99 per month). In addition to accessing the service through the web interface, it is possible to access it through clients for Windows, Mac OS and Android, iOS.

OneDrive cloud storage (http://onedrive.com) from Microsoft is integrated with Office365, allowing you to create, edit, save Excel, OneNote, PowerPoint and Word files directly from the application in the cloud. The service allows free storage of 5GB, paid storage from 50GB for $ 1.99 per month, which is twice as expensive as Google Drive.

Dropbox (http://www.dropbox.com) is a cloud storage that provides 2GB of space for free, but allows you to increase this amount to 48GB by fulfilling a number of conditions (invite a friend, view a review about Dropbox, install Dropbox on your computer, upload files in the Dropbox folder, install Dropbox on other computers that you have access to, share it with friends and colleagues, install the app on mobile devices). Paid storage has a capacity of 1TB and costs € 9.99 per month. Dropbox's strengths are ease of use and speed. In order to put files in the cloud, you just need to put the files in the Dropbox folder on your computer, open access to it and synchronize with the desired device. When editing files previously placed in the cloud, only the changed part is copied to the server. Dropbox allows you to recover data after it was deleted from the server, as well as view the history of file changes for 30 days. For privacy, Dropbox offers BoxCryptor, a tool that encrypts files before transferring them to the cloud.

The most budgetary cloud storage is Mega (https://mega.co.nz). The starting free volume is 50GB, and 4TB per month costs $ 8.33. A feature of this storage is privacy concerns. Data is encrypted in the browser, transferred to the cloud, decryption keys are not published in the public domain, but transferred between users who trust each other.

Yandex.Disk (http://disk.yandex.ru/) is a cloud storage that provides free 10GB, making it possible to expand the free volume up to 60GB by participating in promotions. For $ 0.5 per month, you can purchase an additional 10GB, the cost of 1TB is approximately $ 3.5. Yandex.Disk is integrated into the Microsoft Office suite, and also makes it possible to automatically download photo and video files from digital cameras and external storage media.

[email protected] (https://cloud.mail.ru/) - cloud storage from Mail.ru, which allows free storage of 25 GB, accessible via mobile applications for Android and iOS, a client for Linux. You can automatically upload photos from your phone to the cloud via mobile apps.

Amazon Web Services ( https://aws.amazon.com ) - a cloud services platform that supports various storage options (object storage, block storage, file system storage, archive storage, integrated storage), various network solutions (virtual private cloud, direct connection, load balancing), data processing and database formation tools , corporate applications and mobile services. Free use of the platform is possible for the first 12 months, and then a fee will be charged for those services that are used.

You can supplement the list of the listed cloud storages with the following cloud systems Bitcasa (http://bitcasa.com), Yunpan360 (http://yunpan.360.cn/), 4shared (http://www.4shared.com), SugarSync (https : //www.sugarsync.com), Box.net (http://box.net), iDrive (http://www.idrive.com), OpenDrive (http://www.opendrive.com), Syncplicity (http://www.syncplicity.com), MediaFire (http://www.mediafire.com/), Cubby (https://www.cubby.com/), ADrive (http: //www.adrive. com /).